Yard to Mil/Thou Converter
Convert yards to mils with our free online length converter.
Quick Answer
1 Yard = 36000 mils
Formula: Yard × conversion factor = Mil/Thou
Use the calculator below for instant, accurate conversions.
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Yard to Mil/Thou Calculator
How to Use the Yard to Mil/Thou Calculator:
- Enter the value you want to convert in the 'From' field (Yard).
- The converted value in Mil/Thou will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Length category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Yard to Mil/Thou: Step-by-Step Guide
Converting Yard to Mil/Thou involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Yard = 3.6000e+4 milsExample Calculation:
Convert 10 yards: 10 × 3.6000e+4 = 3.6000e+5 mils
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other length units?
View all Length conversions →What is a Yard and a Mil/Thou?
The yard is a unit of length in the British imperial and United States customary systems of measurement. It is defined as exactly 3 feet or 36 inches, which equals 0.9144 meters.
Precise definition:
- 1 yard = 3 feet (exactly)
- 1 yard = 36 inches (exactly)
- 1 yard = 0.9144 meters (exactly, since 1959)
- 1 yard = 91.44 centimeters
- 1 yard = 914.4 millimeters
Relationship to other units:
- 1 meter = 1.09361 yards (about 9.4% longer)
- 1 mile = 1,760 yards
- 1 furlong = 220 yards
- 1 rod = 5.5 yards
Yard vs. Meter: Key Comparison
This is important for international understanding:
Yard:
- 0.9144 meters (about 91 cm)
- Slightly shorter than a meter
- Used primarily in US, UK, Canada
- Based on foot (3 feet = 1 yard)
Meter:
- 1.09361 yards (about 9% longer)
- Slightly longer than a yard
- Global SI standard
- Based on metric system (100 cm = 1 meter)
Visual comparison:
- A meter stick is about 3.37 inches longer than a yardstick
- 100 yards = 91.44 meters (football field)
- 100 meters = 109.36 yards (Olympic track straightaway)
Mental approximation: For quick estimates, consider 1 yard ≈ 1 meter (about 9% difference is often negligible for casual use).
What is a Mil?
A mil (also called thou) is a unit of length in the imperial measurement system equal to one thousandth of an inch. The mathematical definition is:
1 mil = 0.001 inch = 1/1000 inch = 25.4 micrometers (μm) = 0.0254 millimeters
The mil is not a metric unit and should not be confused with the millimeter (mm), despite similar-sounding names. This confusion is one of the most common measurement errors in international manufacturing:
- 1 mil (imperial) = 0.0254 mm = 25.4 μm
- 1 millimeter (metric) = 39.37 mils = 1,000 μm
The mil exists as a natural subdivision of the inch, providing a convenient decimal-based measurement for very small imperial dimensions without resorting to awkward fractions like 1/1000″.
Mil vs. Thou: Regional Terminology
The terms "mil" and "thou" are completely interchangeable and refer to the exact same measurement:
- Mil: Predominant in American English, technical documentation, industry standards (ASTM, ANSI), and scientific contexts. The name derives from Latin "mille" (thousand).
- Thou: Common in British English shop-floor terminology, machining, and colloquial engineering speech. It's an abbreviated form of "thousandth" (of an inch).
Example usage:
- American engineer: "The coating should be 5 mils thick."
- British machinist: "Machine this to within 2 thou tolerance."
- Both mean the same thing: 0.005″ and 0.002″ respectively.
Decimal Imperial vs. Fractional Imperial
The mil represents a decimal approach to imperial measurement, contrasting with the traditional fractional approach:
Fractional imperial (traditional):
- 1/2″, 1/4″, 1/8″, 1/16″, 1/32″, 1/64″
- Awkward for very small measurements
- Difficult to add/subtract without common denominators
Decimal imperial (mils/thousandths):
- 0.500″ (500 mils), 0.250″ (250 mils), 0.125″ (125 mils)
- Easy arithmetic: 5 mils + 3 mils = 8 mils
- Natural compatibility with digital calipers and micrometers
Engineering drawings often show both: 0.250″ (1/4″) for clarity, but critical tolerances are always specified in decimal thousandths: ±0.005″ (±5 mils), never ±1/200″.
Mils in Wire Gauge Systems
American Wire Gauge (AWG) uses diameter in mils as the basis for its numbering system, though the relationship is logarithmic rather than linear:
| AWG Size | Diameter (mils) | Diameter (mm) | Common Use | |----------|----------------|---------------|------------| | 0000 (4/0) | 460 mil | 11.7 mm | Heavy power cables | | 00 (2/0) | 365 mil | 9.3 mm | Welding cable | | 10 AWG | 102 mil | 2.6 mm | Household 30A circuits | | 14 AWG | 64 mil | 1.6 mm | Household 15A circuits | | 18 AWG | 40 mil | 1.0 mm | Lamp cords, doorbells | | 22 AWG | 25 mil | 0.64 mm | Solid hookup wire | | 30 AWG | 10 mil | 0.25 mm | Wire-wrap wire | | 40 AWG | 3 mil | 0.08 mm | Magnet wire (coils) |
The AWG system was established in the 1850s based on the number of times wire was drawn through reducing dies, with each gauge step representing approximately a 20% reduction in diameter (factor of √2 for cross-sectional area).
Note: The Yard is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Mil/Thou belongs to the imperial/US customary system.
History of the Yard and Mil/Thou
The origin of the yard is uncertain, with historical links possibly related to the length of a stride or the distance from the nose to the fingertip of an outstretched arm (associated with King Henry I of England, though likely apocryphal). It became a standard unit in England for measuring cloth and land, and was later precisely defined relative to the meter.
Early Origins (Pre-1000s)
Ancient roots:
The yard likely evolved from multiple ancient measurement systems:
Saxon "gerd" or "gyrd":
- Old English word meaning "stick," "rod," or "measure"
- Wooden measuring rods used by Anglo-Saxon merchants
- Roughly similar to modern yard but not standardized
Double cubit theory:
- Ancient cubit = elbow to fingertip (~18 inches)
- "Double cubit" = 36 inches = 1 yard
- Used by Romans, Egyptians, Babylonians
Body measurement origins:
- Stride length: Average adult pace (~1 yard)
- Arm span: Nose to fingertip of outstretched arm (apocryphal King Henry I story)
- These varied by individual, creating measurement inconsistency
Medieval Standardization (1100s-1500s)
When the yard became official:
1101: King Henry I "body measurement" legend:
- Popular story: Henry I decreed yard = distance from royal nose to extended thumb
- Likely apocryphal but reflects need for standardization
- Real achievement: Establishing royal standards to replace local variations
1266: Statute of Westminster under Henry III:
- First legal definition of the yard in English law
- Established: 1 yard = 3 feet (official relationship)
- Created iron "yard standards" kept at Westminster Palace
- Cloth merchants required to use standardized yards
1305: Edward I measurement reforms:
- Continued standardization efforts
- "Ell" (45 inches) used for some cloth, but yard became dominant
- Penalties for merchants using incorrect measures
1400s-1500s: Physical yard standards:
- Bronze and brass "yard bars" created as references
- Kept at London's Guildhall and markets
- Regional variations persisted despite standards
Tudor Era Refinement (1500s)
More precise definitions:
1588: Elizabethan Yard Standard:
- Queen Elizabeth I commissioned official "Imperial Standard Yard"
- Made of bronze with precise markings
- Stored at Westminster Palace (lost in 1834 fire)
- Used to verify merchant yardsticks
Textile trade importance:
- England's wool and cloth trade drove standardization
- Fabric sold "by the yard" required consistent measurement
- Export trade demanded international recognition
British Imperial Standardization (1800s)
Scientific precision era:
1824: Weights and Measures Act:
- Standardized imperial units across British Empire
- Yard officially defined in relation to physical prototype
- "Imperial Standard Yard" bar created
1834: Westminster Fire disaster:
- Fire destroyed Houses of Parliament
- Lost original yard standards, including Elizabethan bar
- Created measurement crisis requiring new standards
1855: New Imperial Standard Yard:
- Parliament commissioned replacement yard standard
- Defined as 36/39.370113 meters (based on contemporary meter definition)
- Bronze bar kept at constant temperature (62°F)
- Multiple copies distributed across British Empire
American Divergence (1800s-1950s)
US develops separate standard:
1790s-1830s: Early US measurements:
- United States inherited British yard from colonial era
- No official US standard until 1830s
- State and local variations common
1832: US Office of Weights and Measures:
- Created to standardize American measurements
- Obtained copies of British yard standards
- But slight differences existed between US and UK prototypes
1866: US Metric Act:
- Congress authorized metric system use
- Defined meter-to-yard relationship: 1 meter = 39.37 inches
- Still preserved traditional yard for common use
1893: Mendenhall Order:
- US officially defined yard in terms of meter
- 1 yard = 3,600/3,937 meters = 0.914401829 meters
- Slightly different from British yard (0.9144 m)
- Created UK-US measurement discrepancy
International Unification (1959)
Finally, one global yard:
July 1, 1959: International Yard and Pound Agreement:
- Signed by US, UK, Canada, Australia, New Zealand, South Africa
- Defined: 1 yard = exactly 0.9144 meters
- 1 inch = exactly 25.4 millimeters (derived)
- Unified measurements across English-speaking world
Why this mattered:
- Eliminated UK-US discrepancy (0.914401829 vs 0.9144 m)
- Simplified international trade and engineering
- Difference was tiny (2 parts per million) but critical for precision work
Survey yard exception:
- US land surveys continued using old definition until 2023
- "US Survey Yard" = 0.91440183 meters (pre-1959 standard)
- Created confusion in mapping/GIS
- January 1, 2023: US officially retired survey yard, adopted international yard
Modern Era (1960s-Present)
Metric pressure and yard persistence:
1960s-1970s: Global metrication:
- Most British Commonwealth nations adopted metric system
- Australia (1970s), Canada (1970s), UK (partially 1960s-80s)
- Yard usage declined in favor of meters
United States resistance:
- Rejected metric conversion despite 1975 Metric Conversion Act
- Yard remains standard for fabric, sports, construction
- Coexists with metric in science, medicine, military
Current status:
- Primary use: United States (everyday measurement)
- Limited use: UK (road distances in miles/yards, sports fields)
- Legacy use: Canada (construction, real estate alongside meters)
- Declining: Elsewhere, replaced by meters
Ancient and Medieval Precision (Before 1700)
Before the Industrial Revolution, precision measurement was limited by available tools. Ancient civilizations measured small lengths using:
- Barleycorns: 1 inch = 3 barleycorns (still referenced in shoe sizing)
- Hair breadth: Approximately 1/48 of an inch (about 21 mils)
- Poppy seed: Medieval unit ≈ 1/72 inch (14 mils)
These natural standards were inconsistent but adequate for carpentry, masonry, and traditional crafts where tolerances of 1/16″ to 1/32″ were acceptable. Precision metalworking (locksmithing, clockmaking, weapon-smithing) relied on master craftsmen's skill and direct comparison to reference standards rather than numerical measurement.
The finest medieval measurements were in clock and instrument making, where tolerances approaching 1/100″ (10 mils) were occasionally achieved, but not reliably measured or documented.
Industrial Revolution and the Birth of Precision (1750-1850)
The transformation of manufacturing from craft to industry created an urgent need for precision measurement:
1775-1800: John Wilkinson's cylinder boring machine (1775) achieved tolerances within 1/20″ (50 mils) for steam engine cylinders—revolutionary at the time, enabling James Watt's efficient steam engines.
1800-1840: Interchangeable parts manufacturing emerged. Eli Whitney's 1798 contract to produce 10,000 muskets with interchangeable parts required consistent tolerances around 1/32″ (31 mils), though he struggled to achieve this consistently.
1840s: Joseph Whitworth revolutionized precision measurement:
- Invented the first practical micrometer (1840s), capable of measuring to 0.001″ (1 mil)
- Developed precision surface plates and scrapers
- Standardized screw threads with tolerances of a few thousandths
- Established the "thou" as the standard British precision unit
Whitworth's work meant that for the first time, machinists could reliably measure and verify work to within one thousandth of an inch, making the mil/thou a practical working unit rather than a theoretical ideal.
1850s: American System of Manufacturing (Colt, Robbins & Lawrence, Singer) adopted decimal measurements in thousandths for gauging and inspection, establishing "mils" in American technical vocabulary.
Standardization and Proliferation (1850-1920)
1860s-1880s: Development of precision measuring instruments:
- Vernier calipers graduated in thousandths
- Micrometer calipers (marketed by Brown & Sharpe from 1867)
- Dial indicators (from 1890s) showing 0.001″ divisions
1857: American Wire Gauge (AWG) standardized by J. R. Brown, using wire diameter in mils as the basis.
1880s-1900s: Paint and coating industries adopted mils for dry film thickness:
- Paint manufacturers specified coverage rates based on mils of dry film
- Wet film thickness gauges calibrated in mils
- Quality standards (e.g., U.S. Navy specifications) required minimum coating thickness in mils
1900-1920: Sheet metal gauges proliferated (ironically, these use arbitrary numbering systems, but actual thickness is specified in decimal inches/mils):
- Manufacturer's Standard Gauge (MSG) for steel
- Birmingham Wire Gauge (BWG)
- Confusion from multiple gauge systems led to increasing use of direct mil specifications
1916: SAE (Society of Automotive Engineers) founded, establishing thousands of specifications with tolerances in thousandths of an inch for automotive parts.
Electronics Age and Micro-Precision (1920-1980)
1930s-1940s: Electronics manufacturing adopted mils for:
- Wire insulation thickness (enamel on magnet wire: 0.5-2 mils)
- Capacitor dielectric thickness
- Vacuum tube electrode spacing
1943: Printed Circuit Board (PCB) invention (Paul Eisler, 1943; mass production 1950s):
- Copper foil thickness: 1.4 mils (1 oz/ft²), 2.8 mils (2 oz/ft²)
- Trace width: typically 5-15 mils for signal traces
- Spacing between traces: 5-8 mils minimum in early designs
- PCB substrate thickness: 62 mils (1.57 mm) became standard
1950s-1960s: Plastic film industry standardized thickness in mils:
- Polyethylene film (bags, wrap): 0.5-6 mils
- Polyester film (Mylar): 0.5-10 mils
- Vinyl flooring underlayment: 6-20 mils
1960s: Integrated circuit (IC) manufacturing pushed precision far beyond mils:
- Early transistors: features measured in tens of mils
- By 1970: features approaching 100 microinches (0.1 mil)
- The mil remained relevant for IC package dimensions, lead spacing, and encapsulation thickness
1975: ANSI/ASTM standards codified mil-based specifications for coating thickness, plastic film, and adhesive tape across dozens of industries.
Modern Era and Metrication Resistance (1980-Present)
1980s-1990s: Global metrication movement:
- Britain officially metricated in 1965-1995, but "thou" persisted in machine shops
- U.S. industries largely resisted metrication in favor of established decimal-inch (mil) systems
- Aerospace, defense, and automotive industries retained imperial specs due to:
- Enormous legacy of existing designs, tooling, and parts libraries
- Cost of converting decades of technical documentation
- Risk of conversion errors (Mars Climate Orbiter lost in 1999 due to metric/imperial confusion)
1990s-2000s: PCB design and microelectronics:
- PCB CAD software (OrCAD, Altium, Eagle) defaulted to mil grid spacing (5 mil, 10 mil, 25 mil grids)
- Modern PCB fabrication: 3-4 mil traces/spaces achievable in standard processes
- Advanced processes: sub-mil features (0.5 mil), but package and board dimensions still in mils
2000s-Present: Hybrid metric/imperial usage:
- American manufacturing: Part dimensions often in inches/mils, tolerances in mils
- International suppliers: Provide both metric and mil equivalents
- 3D printing: Software often accepts both (mil settings for layer height, nozzle diameter)
- Coating industry: Paint thickness gauges typically show both mils and microns
Present day: The mil remains dominant in:
- American PCB and electronics manufacturing
- U.S. aerospace and defense (military specifications)
- Coating and painting (ASTM standards)
- Plastic film and flexible packaging
- American Wire Gauge system
- Machining tolerances in U.S. shops
Common Uses and Applications: yards vs mils
Explore the typical applications for both Yard (imperial/US) and Mil/Thou (imperial/US) to understand their common contexts.
Common Uses for yards
Textiles and Fabric Industry
Measuring fabric length (often sold by the yard).
Why yards persist in fabric:
- Historical: English wool trade established "yard goods" standard
- Bolt widths designed around yard fractions
- Cutting tables marked in yards
- Pattern instructions written in yards
Standard practices:
- Minimum purchase: Often 0.25 yard (9 inches)
- Common increments: Sold in 1/8 yard (4.5 in), 1/4 yard, 1/2 yard, 1 yard
- Remnants: Odd lengths sold at discount
- Wholesale: Fabric bolts typically 10-20 yards
International comparison:
- Metric countries: Fabric sold by meter
- Pattern conversion: 1 yard ≈ 0.91 meters (patterns provide both)
Sports Field Dimensions
Dimensions of sports fields (e.g., American football, soccer pitch lengths can be expressed in yards).
American football:
- Standard 100-yard × 53⅓-yard field
- Universal across high school, college, NFL
- Goal posts width: 18.5 feet (6.17 yards)
Soccer/association football:
- US youth fields: Often expressed in yards (e.g., "60 yards × 40 yards")
- International: Meters (100-110m × 64-75m)
- Conversion needed: FIFA-sized field ~120 yards × 80 yards
Cricket:
- Pitch length: 22 yards (20.12 meters) between wickets
- Boundary: Varies, typically 65-90 yards radius
Lacrosse:
- Men's field: 110 yards × 60 yards
- Women's field: Varies, typically 120 yards × 70 yards
Landscaping and Gardening
Landscaping and gardening measurements (e.g., yards of mulch).
Bulk materials:
- Mulch: "$35 per cubic yard delivered"
- Topsoil: Cubic yards for garden beds
- Gravel/crushed stone: Driveway base in cubic yards
- Compost: Bulk delivery by cubic yard
Coverage calculations:
- 1 cubic yard of mulch: Covers ~100 sq ft at 3-inch depth
- 1 cubic yard of topsoil: Covers ~100 sq ft at 3-inch depth
- Landscape fabric: Sold by linear yard (typically 3-4 feet wide)
Garden planning:
- Raised bed dimensions: "4 yards long × 1 yard wide"
- Irrigation: Pipe and hose measured in yards
- Hedge spacing: "Plant every 1 yard for privacy"
Short to Medium Distance Measurement
Shorter road distances or property dimensions in the US and UK.
Road signage (UK):
- Warning signs: "200 yards ahead"
- Distance markers: "Services 300 yards"
- US: Mostly uses feet for short road distances
Property and real estate:
- Lot frontage: "100 yards of waterfront"
- Setbacks: Building code requirements in yards
- Fencing: "Install 200 yards of fencing"
Navigation:
- GPS directions: "In 50 yards, turn right" (some devices)
- Marine navigation: Prefer nautical miles, but yards for close quarters
- Aviation: Use feet for altitude, nautical miles for distance
Military and Defense
Historically significant:
Rifle ranges:
- 100-yard zero: Common rifle sight-in distance
- 200/300/500 yards: Marksmanship qualification distances
- Long-range shooting: Expressed in yards (e.g., "1,000-yard shot")
Military exercises:
- Formations: Squad spacing in yards
- Radio calls: "Enemy position 300 yards north"
- Artillery: Modern systems use meters, but yards persist in US training
When to Use mils
1. Precision Manufacturing and Machining
The mil is the fundamental tolerance unit in American manufacturing:
Engineering drawings and blueprints:
- Nominal dimensions in decimal inches: 1.250″, 0.375″
- Tolerances in thousandths: ±0.005″ (±5 mils), ±0.002″ (±2 mils)
- Geometric dimensioning and tolerancing (GD&T): Position tolerance ⌖ 0.010″ (10 mils)
Quality control and inspection:
- Calipers and micrometers graduated in 0.001″ (1 mil) divisions
- Dial indicators show 0.001″ or 0.0001″ (0.1 mil) graduations
- Coordinate measuring machines (CMM) measure to ±0.1 mil or better
- Pass/fail gauges: "Go" and "No-Go" plugs/rings differ by a few mils
Real-world tolerances by industry:
- General fabrication: ±5-10 mils (±0.005-0.010″)
- Automotive production: ±2-5 mils typical
- Aerospace critical parts: ±0.5-2 mils
- Medical implants (hip, knee): ±0.2-1 mil
- Semiconductor equipment: ±0.1 mil (±100 microinches)
Example: A shaft specified as Ø 1.000″ ± 0.002″ must measure between 0.998″ and 1.002″ (within ±2 mils). A shaft measuring 1.003″ (3 mils over) would be rejected.
2. Coating Thickness Measurement
Paint, plating, and protective coating thickness is universally measured in mils in American industry:
Paint inspection (wet film thickness gauges):
- Notch gauges (comb-style): Teeth graduated in mils (2, 4, 6, 8, 10 mils)
- Painter inserts gauge into wet paint; highest clean tooth indicates thickness
- Ensures proper coverage to meet specification (e.g., "apply to 6 mils wet film")
Dry film thickness (DFT) measurement:
- Magnetic gauges (ferrous substrates): Reed sensor or Hall effect, calibrated in mils
- Eddy current gauges (non-ferrous): For aluminum, brass, copper substrates
- Ultrasonic gauges: For non-metallic coatings on any substrate
Industry specifications:
- SSPC-PA 2 (paint inspection): Requires DFT measurement in mils
- U.S. Navy painting specs: Minimum DFT requirements (e.g., 5-7 mils for topcoat)
- Automotive OEM specs: Total paint system 4-6 mils
- Industrial maintenance coatings: Often 8-15 mils for severe environments
Example: A steel bridge specification might require: "Apply epoxy primer to 5-8 mils DFT, followed by polyurethane topcoat to 3-5 mils DFT." Inspectors measure at multiple points; any reading below minimum triggers rework.
Galvanizing and plating:
- Hot-dip galvanizing: ASTM A123 requires minimum 2.0 mils (for <1/4″ thick steel)
- Chrome plating: 0.5-1 mil decorative, 8-10 mils hard chrome (wear resistance)
- Anodizing (aluminum): Type II = 0.2-0.7 mils, Type III (hard anodize) = 2-4 mils
3. Plastic Film and Flexible Packaging
Plastic film thickness is specified in mils in the U.S. packaging industry:
Food packaging films:
- Shrink wrap: 2-4 mils (60-100 μm)
- Stretch wrap (pallet wrap): 12-20 gauge = 0.5-0.8 mil (gauge ≠ mils, confusingly)
- Vacuum seal bags (FoodSaver): 3-4 mils
- Frozen food bags: 2-3 mils
- Thicker film = better puncture resistance, higher material cost
Construction and industrial films:
- Vapor barriers (under-slab): 6-10 mils required by building codes
- Construction tarps: 5-12 mils depending on duty
- Agricultural greenhouse film: 4-6 mils (UV-stabilized)
- Geomembrane liners (landfills, ponds): 20-100 mils
Adhesive tapes:
- Scotch tape (Transparent): 1-1.5 mils
- Masking tape: 5-7 mils total thickness
- Duct tape: 10-12 mils
- Double-sided foam tape: 30-60 mils
- Specification includes backing + adhesive thickness
Industry standards:
- ASTM D6988: Standard specification for polyethylene film (thickness in mils)
- ASTM D374: Method for measuring tape thickness (to 0.1 mil)
Example: A customer ordering "6-mil poly sheeting" for a concrete vapor barrier receives polyethylene film exactly 0.006″ (6 mils = 0.15 mm) thick, ensuring compliance with IRC building code.
4. Electronics and Printed Circuit Boards
PCB design and manufacturing is dominated by mil-based dimensions in the United States:
PCB design software (Altium, Eagle, KiCAD, OrCAD):
- Default grid spacing: 50 mils, 25 mils, 10 mils, 5 mils, 1 mil
- Component libraries use 100-mil pin spacing for through-hole parts
- Trace width and clearance rules specified in mils
Design rules and capabilities:
- Standard PCB fabrication (budget services):
- Minimum trace width: 6 mils
- Minimum spacing: 6 mils
- Via drill: 8-10 mils
- Copper weight: 1 oz (1.4 mils)
- Advanced PCB fabrication:
- Minimum trace/space: 3 mil / 3 mil
- Microvias: 4-6 mil drill
- HDI (high-density interconnect): sub-mil features
Copper thickness selection:
- 1 oz copper (1.4 mils): Standard for signal layers, adequate for currents <3A
- 2 oz copper (2.8 mils): Power planes, higher current capacity (5-10A per trace)
- 3-4 oz copper (4.2-5.6 mils): Power electronics, automotive
- Current-carrying capacity increases with thickness (more copper = less resistance = less heat)
PCB stackup (multilayer boards):
- 4-layer board example:
- Top copper: 1.4 mils (1 oz)
- Prepreg: 7 mils
- Inner layer 1 (ground): 1.4 mils
- Core: 47 mils
- Inner layer 2 (power): 1.4 mils
- Prepreg: 7 mils
- Bottom copper: 1.4 mils
- Total: 67 mils (1.7 mm)
Soldermask and silkscreen:
- Soldermask (green coating): 0.8-1.2 mils thickness
- Silkscreen (white text): 0.5-1 mil
- Surface finish (ENIG gold): 1-2 microinches (0.001-0.002 mil)
5. Wire Gauge and Cable Manufacturing
American Wire Gauge (AWG) is fundamentally based on diameter in mils:
AWG diameter formula:
- Each gauge step represents approximately a 1.123× change in diameter (10 steps = 1 decade = 10× area change)
- AWG 10 = 102 mils diameter
- AWG 20 = 32 mils diameter
- AWG 30 = 10 mils diameter
Wire insulation thickness (in mils over conductor diameter):
- Thin-wall insulation: 4-8 mils
- Standard insulation: 15-30 mils
- High-voltage insulation: 30-60+ mils
- Specification: "22 AWG with 10 mil insulation" = 25 mil conductor + 20 mil insulation total = 45 mil overall diameter
Magnet wire (enameled copper for motors, transformers):
- AWG 28-40 common for small coils
- Enamel coating: 0.5-2 mils depending on temperature rating
- Grade 1 (thinnest): 0.5-0.8 mil enamel
- Grade 2 (standard): 1-1.5 mil enamel
- Grade 3 (heavy build): 2-3 mil enamel
- Thicker enamel = better insulation, lower packing density in coil
Cable jacket thickness:
- Ethernet Cat6 cable jacket: 20-30 mils
- Power cord (SJOOW): 60-80 mils
- Mining cable: 125-250 mils (extreme abrasion resistance)
6. Sheet Metal and Gauge Systems
Sheet metal thickness is specified in gauge numbers, but actual thickness is in decimal inches (mils):
Manufacturer's Standard Gauge (steel):
- 10-gauge = 135 mils (0.1345″)
- 14-gauge = 75 mils (0.0747″)
- 20-gauge = 36 mils (0.0359″)
- 24-gauge = 24 mils (0.0239″)
Confusion and standardization issues:
- Gauge numbers are not universal: steel gauge ≠ aluminum gauge ≠ galvanized gauge
- Modern practice: Always specify in decimal inches (mils) to avoid ambiguity
- Example: "0.060″ aluminum" (60 mils) instead of "14-gauge aluminum"
HVAC ductwork:
- Residential ducts: 24-26 gauge (18-30 mils)
- Commercial ducts: 20-22 gauge (33-42 mils)
- Galvanized coating adds 2-5 mils to thickness
Automotive body panels:
- Hood outer skin: 28-30 mils (0.7-0.8 mm)
- Door outer skin: 26-28 mils
- Roof panel: 28-32 mils
- Frame rails: 90-120 mils (2.3-3.0 mm)
7. Quality Control and Standards Compliance
Mil-based specifications appear in thousands of ASTM, ANSI, SAE, and military standards:
ASTM coating standards:
- ASTM D3359: Adhesion of coatings (measured after cutting through coating, thickness in mils)
- ASTM D1186: Paint film thickness (magnetic gauges calibrated in mils)
- ASTM D6132: Nondestructive measurement of dry film thickness (mils)
Military specifications (MIL-SPEC):
- MIL-DTL-53030: Primer coating, epoxy, 2-3 mils DFT
- MIL-PRF-85285: Coating, polyurethane, aircraft, 1.5-2.5 mils
- Compliance requires thickness measurement at specified intervals
Building codes and construction:
- International Residential Code (IRC): Vapor retarders minimum 6 mils
- Roofing underlayment: Minimum thickness specifications in mils
- Window film (safety/security): 4-14 mils for various protection levels
Automotive and aerospace:
- SAE J1960: Brake hose specifications (wall thickness in inches/mils)
- AS9100 (aerospace quality): Dimensional inspections recorded in mils
- Engine bearing clearances: Specified in mils (e.g., 1.5-2.5 mils for main bearings)
Additional Unit Information
About Yard (yd)
How many feet are in a yard?
There are exactly 3 feet (ft) in 1 yard (yd). This is the fundamental relationship defining the yard. For example: 5 yards = 15 feet, 10 yards = 30 feet, and 100 yards (a football field) = 300 feet.
How many inches are in a yard?
There are exactly 36 inches (in) in 1 yard (yd). Since 1 yard = 3 feet and 1 foot = 12 inches, multiply: 3 × 12 = 36 inches. This is useful for fabric cutting and precise measurements.
Is a yard longer or shorter than a meter?
A yard (0.9144 m) is slightly shorter than a meter (1 m) by approximately 9.4% or about 3.37 inches. Think of it this way: 100 yards = 91.44 meters, or conversely, 100 meters = 109.36 yards. A yardstick is visibly shorter than a meter stick when placed side by side.
How many yards are in a mile?
There are 1,760 yards in 1 mile (statute mile). This means a half-mile = 880 yards, and a quarter-mile = 440 yards. For reference, a standard running track is 440 yards (or 400 meters in modern tracks), representing one-quarter of a mile.
Why is fabric sold by the yard?
Fabric is sold by the yard in the US due to historical English textile trade practices from the medieval period when the yard became the standard cloth measurement. Fabric bolts are manufactured in yard-friendly widths (typically 36, 45, 54, or 60 inches), and cutting tables are marked in yards. Sewing patterns specify fabric requirements in yards, making it the standard for the American crafting and fashion industries. Internationally, fabric is sold by the meter in metric countries.
How do I measure a yard without a ruler?
Body-based approximations:
- Adult stride: Average adult walking pace is approximately 1 yard (may vary by height)
- Arm span approximation: Nose to fingertip of outstretched arm is roughly 1 yard (the apocryphal King Henry I method)
- 3 shoe lengths: Average adult shoe is about 12 inches, so 3 shoes ≈ 36 inches = 1 yard
Household objects:
- Door height: Standard door is 80 inches (2.22 yards)
- Floor tiles: 12-inch square tiles → 3 tiles in a row = 1 yard
- Credit card: 3.37 inches wide → 10.7 cards = 1 yard (not practical, but mathematically interesting)
Best method: Mark a stick or string at 36 inches using a ruler once, then use it as a reusable yard measure.
What is a "square yard"?
A square yard (yd²) is a unit of area equal to a square measuring 1 yard on each side. Since 1 yard = 3 feet, 1 square yard = 9 square feet (3 ft × 3 ft). This is used for measuring carpet, flooring, landscaping coverage, and room areas. For example, a 10 ft × 12 ft room = 120 square feet = 13.33 square yards.
What is a "cubic yard"?
A cubic yard (yd³) is a unit of volume equal to a cube measuring 1 yard on each side. Since 1 yard = 3 feet, 1 cubic yard = 27 cubic feet (3 ft × 3 ft × 3 ft). This is the standard unit for ordering concrete, mulch, soil, gravel, and other bulk materials in the US. For example, a concrete truck typically carries 10 cubic yards, and 1 cubic yard of mulch covers approximately 100 square feet at 3-inch depth.
Why do American football fields use yards?
American football fields use yards because the sport originated in the United States in the late 1800s when imperial units were the standard measurement system. The 100-yard field length provides convenient divisions: 4 quarters of 25 yards each, 10-yard first-down increments, and easy mental arithmetic for players and fans. Changing to meters (100m = 109.36 yards) would create awkward field dimensions and disrupt the sport's traditional structure. The yard remains deeply embedded in football culture and rule books.
Are yards still used in the UK?
Yes, but usage is mixed and declining. The UK officially adopted the metric system in the 1960s-1990s, but yards persist in certain contexts:
- Road signs: Distances under 1 mile often shown in yards ("Services 200 yards")
- Sports: Cricket (22-yard pitch), some golf courses
- Informal speech: Older generations may say "a few yards away"
- Fabric shops: Some still sell by the yard, but meters increasingly common
Not used: Most construction, engineering, education now use meters. Younger generations primarily think in metric.
Can I use yards and meters interchangeably?
For rough estimates: Yes (about 10% difference often negligible) For precision work: No (9.4% difference accumulates)
When interchangeable works:
- Casual conversation ("it's about 50 yards/meters away")
- Rough project planning
- Approximate sports distances
When you need exact conversion:
- Fabric orders (5 yards ≠ 5 meters - you'd be short 43 cm)
- Construction blueprints
- Athletic competition (100-yard dash ≠ 100-meter dash)
- International trade
Best practice: Convert explicitly using 1 yard = 0.9144 meters for any situation requiring accuracy.
About Mil/Thou (mil)
Is a mil the same as a millimeter?
No—they are very different units, despite similar names.
- 1 mil (imperial) = 0.001 inches = 0.0254 mm = 25.4 micrometers
- 1 millimeter (metric) = 0.001 meters = 39.37 mils
Key difference: 1 millimeter is approximately 40 times larger than 1 mil. Confusing these units results in massive errors (40× too thick or thin).
Origin of confusion: "Mil" sounds like an abbreviation for "millimeter," but it actually comes from the Latin "mille" (thousand), meaning one thousandth of an inch. In some non-English languages, "mil" or "mil." is used as slang for millimeter, compounding confusion in international contexts.
Prevention: Always write units explicitly—"6 mils (0.15 mm)" or "0.2 mm (7.9 mils)"—in international specifications.
What does 'thou' mean, and is it the same as a mil?
Yes—"thou" and "mil" are exactly the same measurement: one thousandth of an inch (0.001″).
Regional differences:
- "Mil" is standard in American technical documentation, industry standards (ASTM, ANSI, SAE), and scientific publications.
- "Thou" is common in British English shop-floor terminology, machining, and colloquial engineering speech.
Etymology:
- "Mil" comes from Latin "mille" (thousand)
- "Thou" is an abbreviation of "thousandth" (of an inch)
Usage examples:
- American engineer: "Tolerance is plus or minus five mils."
- British machinist: "Take another two thou off the diameter."
- Both mean exactly: 0.005″ and 0.002″ respectively.
Documentation practice: Technical drawings and specifications predominantly use "mil" or the decimal notation (0.001″), while "thou" appears more in verbal communication and informal notes.
How many mils are in an inch?
Exactly 1,000 mils = 1 inch by definition.
The mil is defined as one thousandth of an inch:
- 1 mil = 0.001″
- 1 inch = 1,000 mils
Common fractions converted to mils:
- 1/2″ = 500 mils
- 1/4″ = 250 mils
- 1/8″ = 125 mils
- 1/16″ = 62.5 mils
- 1/32″ = 31.25 mils
- 1/64″ = 15.625 mils
This decimal subdivision makes arithmetic much easier than traditional fractional inches (no need to find common denominators).
Why do we still use mils instead of millimeters?
Several practical and historical reasons explain the mil's persistence in American industry despite global metrication:
1. Legacy infrastructure (strongest reason):
- Billions of dollars invested in tooling, fixtures, gauges, and manufacturing equipment calibrated in inches/mils
- Converting existing designs and technical documentation is prohibitively expensive and risky
- Critical industries (aerospace, defense, medical) have decades of proven designs that cannot be easily converted
2. Compatibility and interchangeability:
- Replacing a part requires exact dimensional compatibility
- Mixed mil/metric systems in a single product line risk catastrophic errors (e.g., 1999 Mars Climate Orbiter loss due to metric/imperial confusion)
- Entire supply chains (thousands of vendors) must convert simultaneously for compatibility
3. Established standards:
- American Wire Gauge (AWG) is based on mils
- ASTM, ANSI, SAE, and military specifications (MIL-SPEC) use mils
- Rewriting thousands of standards documents is a monumental undertaking
4. Practical advantages in some contexts:
- PCB design: 100-mil (0.1″) pin spacing is convenient, memorable, and grid-friendly
- Engineering calculations: Tolerances like "±5 mils" are intuitive to experienced engineers
- Decimal-inch system avoids fractional arithmetic while maintaining imperial base
5. Economic inertia:
- No compelling economic driver for conversion in purely domestic manufacturing
- Cost of conversion (training, documentation, tooling) outweighs benefits in mature industries
6. Cultural and educational factors:
- American engineers trained in decimal-inch system for generations
- Familiarity breeds efficiency—experienced machinists "think in mils"
Counterpoint: Industries with strong international ties (automotive, consumer electronics) increasingly use dual dimensioning (both mils and mm) or have shifted to metric. New designs often start in metric, but maintenance of existing imperial products ensures mils remain relevant for decades.
How do I convert mils to micrometers (microns)?
Multiply mils by 25.4 to get micrometers (μm):
Formula: μm = mils × 25.4
Examples:
- 1 mil × 25.4 = 25.4 μm
- 5 mils × 25.4 = 127 μm
- 10 mils × 25.4 = 254 μm
- 100 mils × 25.4 = 2,540 μm (= 2.54 mm)
Reverse conversion (micrometers to mils): Divide by 25.4
Formula: mils = μm ÷ 25.4
Examples:
- 50 μm ÷ 25.4 = 1.97 mils (≈ 2 mils)
- 100 μm ÷ 25.4 = 3.94 mils (≈ 4 mils)
- 250 μm ÷ 25.4 = 9.84 mils (≈ 10 mils)
Why 25.4? Because 1 inch = 25.4 mm exactly (by the 1959 international agreement), and 1 mil = 0.001 inch, so:
- 1 mil = 0.001 inch × 25.4 mm/inch = 0.0254 mm = 25.4 μm
Practical use: Coating thickness specifications often appear in both units:
- "Apply to 5 mils (127 μm) dry film thickness"
- Ensures international suppliers understand the requirement
What is 1 mil in metric units?
1 mil = 25.4 micrometers (μm) = 0.0254 millimeters (mm) exactly.
Complete metric equivalents:
- 1 mil = 25.4 μm (most common metric expression for precision work)
- 1 mil = 0.0254 mm (less common, but useful for larger scales)
- 1 mil = 0.0000254 meters
- 1 mil = 25,400 nanometers (semiconductor/optics context)
Reverse:
- 1 micrometer (μm) = 0.03937 mil (≈ 1/25 mil)
- 1 millimeter (mm) = 39.37 mils (≈ 40 mils for quick estimation)
Why exactly 25.4? The 1959 international yard and pound agreement defined:
- 1 inch = 25.4 mm exactly
- Therefore: 1 mil = 0.001 inch = 25.4 μm exactly
This is not an approximation—it's the legal definition linking imperial and metric systems.
How thick is 4 mils?
4 mils = 0.004 inches = 0.1 mm (100 micrometers) — about the thickness of standard printer paper.
Everyday comparisons for 4 mils:
- Two sheets of standard copy paper stacked (each ~4 mils)
- Human hair is roughly 2× thicker (70-100 mils vs. 4 mils)
- Credit card is roughly 7.5× thicker (30 mils vs. 4 mils)
- Fingernail is roughly 5-7× thicker (20-30 mils)
Common uses of 4-mil thickness:
- Printer/copy paper (20 lb bond): 3.5-4.5 mils
- Automotive paint (single coat): 1.5-2 mils base + 1.5-2 mils clear = 4-5 mils total
- Polyethylene sheeting (light-duty drop cloths): 3-4 mils
- House paint (exterior, dry film): 1.5-2 coats × 2 mils each = 4-5 mils
Feeling 4 mils: Too thin to feel accurately with fingers—requires calipers or micrometer to measure precisely.
What is considered a tight tolerance in mils?
"Tight" tolerances depend on the manufacturing process and application, but general industry standards are:
General fabrication and commercial machining:
- Loose tolerance: ±10-20 mils (±0.010-0.020″)
- Standard tolerance: ±5 mils (±0.005″)
- Tight tolerance: ±1-2 mils (±0.001-0.002″)
Precision machining:
- Standard: ±1 mil (±0.001″)
- Tight: ±0.5 mil (±0.0005″)
- Very tight: ±0.1-0.2 mil (±100-200 microinches)
Ultra-precision (grinding, diamond turning):
- Tight: ±0.05 mil (±50 microinches = ±1.3 μm)
- Extremely tight: ±0.01 mil (±10 microinches = ±0.25 μm)
Application examples:
- Engine piston fit: 1-3 mils clearance (0.001-0.003″) — critical for sealing and oil retention
- Bearing journals: ±0.5 mil tolerance — affects bearing life and performance
- Hydraulic valve spool: 0.5-1 mil clearance — controls internal leakage
- Gauge blocks (Grade 0): ±0.05 mil (±50 microinches) — calibration standard
- Optical lens mounts: ±0.1 mil — affects focus and alignment
Cost impact: Tighter tolerances require:
- More precise equipment (CNC machining centers, grinders)
- Slower machining speeds and feeds
- More frequent inspection
- Skilled machinists
- Climate-controlled environment (for extreme precision)
Rule of thumb: Each 10× reduction in tolerance (e.g., ±10 mils → ±1 mil → ±0.1 mil) roughly doubles or triples machining cost.
How do you measure thickness in mils?
Several tools measure thickness in mils, depending on the material and access:
1. Micrometer (most common for solid parts):
- Handheld precision tool with anvil and spindle
- Resolution: 0.001″ (1 mil) for standard micrometers; 0.0001″ (0.1 mil) for digital or vernier micrometers
- How to use: Place object between anvil and spindle, turn thimble until it contacts with light resistance, read measurement
- Accuracy: ±0.0001″ (±0.1 mil) or better when calibrated
- Best for: Solid materials (sheet metal, plastic, gaskets, wire)
2. Digital calipers:
- Resolution: Typically 0.001″ (1 mil) or 0.01 mm
- Easier to read than dial calipers (digital display)
- Less precision than micrometers (±1-2 mils accuracy)
- Best for: Quick measurements, larger parts, non-critical dimensions
3. Coating thickness gauges (for paint/plating):
- Magnetic gauges (ferrous substrates): Reed switch or Hall effect sensor detects distance through non-magnetic coating
- Eddy current gauges (non-ferrous substrates): Measures impedance change due to coating thickness
- Ultrasonic gauges: Sound wave reflection for non-metallic coatings or any substrate
- Resolution: Typically 0.1 mil (2.5 μm) to 1 mil depending on model
- Best for: Paint, powder coating, galvanizing, plating, anodizing on metal substrates
4. Wet film thickness gauges (paint application):
- Notch/comb gauges: Comb with graduated teeth (2, 4, 6, 8, 10 mils)
- How to use: Insert comb perpendicular into wet paint; highest clean tooth (no paint) indicates thickness
- Resolution: Depends on tooth spacing (typically 2 mil increments)
- Best for: Field inspection during painting to ensure proper application
5. Dial indicators (for comparing thickness):
- Measures variation rather than absolute thickness
- Place part on reference surface, indicator plunger contacts top
- Resolution: 0.001″ (1 mil) or 0.0001″ (0.1 mil) for precision models
- Best for: Checking flatness, parallelism, thickness variation across a surface
6. Optical/laser micrometers (non-contact):
- Laser beam measures shadow of object passing through
- Resolution: Sub-mil (0.01-0.1 mil) depending on model
- Best for: Soft materials (rubber, foam) or high-speed production inspection (wire, cable)
Calibration: All precision measuring tools require regular calibration against gauge blocks or calibration standards to maintain accuracy.
Why is PCB design done in mils?
PCB (printed circuit board) design uses mils primarily due to historical legacy and practical convenience in American electronics manufacturing:
1. Component standards based on 100-mil spacing:
- Through-hole components (resistors, ICs, connectors) were standardized with 0.1″ (100 mil) pin spacing in the 1950s-1970s
- Dual in-line packages (DIP): Pins spaced at 100 mil intervals
- Perfboard and breadboards: 100 mil grid for prototyping
- This 100-mil standard became embedded in component libraries and CAD software
2. PCB design grid convenience:
- Grid snapping: CAD software uses grids (50 mil, 25 mil, 10 mil, 5 mil, 1 mil)
- 100 mil grid allows easy component placement aligned with standard pin spacing
- Fractional grids: 50 mil (0.05″), 25 mil (0.025″) for routing between pins
- Metric equivalents (2.54 mm, 1.27 mm, 0.635 mm) are awkward, non-round numbers
3. Trace width and spacing in convenient numbers:
- Typical design rules: 6 mil trace / 6 mil space (easier to remember than "0.15 mm / 0.15 mm")
- High-current traces: 15 mil, 20 mil, 30 mil widths (round numbers)
- Advanced designs: 3 mil / 3 mil minimum capability
4. Standard PCB thickness:
- 62 mils (1.57 mm) is the industry-standard board thickness—originated in imperial measurements
- Thinner boards: 31 mils (0.8 mm), 47 mils (1.2 mm)
- Thicker boards: 93 mils (2.4 mm), 125 mils (3.2 mm)
5. Copper weight in oz/ft² naturally maps to mils:
- 1 oz copper = 1.4 mils thick (34.8 μm)
- 2 oz copper = 2.8 mils thick
- Easy calculation for impedance and current capacity
6. Legacy and tool compatibility:
- Enormous library of existing designs, footprints, and components in mil units
- PCB CAD software (Altium, Eagle, OrCAD, KiCAD) default to mils in U.S. installations
- Converting to metric risks errors and incompatibility with legacy designs
Modern trend: Some international PCB design now uses metric (especially in Europe and Asia), but American designs and military/aerospace specs remain overwhelmingly mil-based. Many CAD tools support dual dimensioning to bridge both systems.
Are mils still relevant today, or is it an obsolete unit?
Mils are absolutely still relevant and widely used in American manufacturing, despite global metrication trends. The unit is not obsolete—it remains the standard in several major industries:
Industries actively using mils today (2020s):
1. Printed circuit board (PCB) and electronics manufacturing:
- Trace widths, spacing, and via sizes specified in mils
- Component libraries and footprints use 100-mil pin spacing
- Standard fabrication capabilities: "6 mil trace / 6 mil space"
2. Aerospace and defense:
- Military specifications (MIL-SPEC) use mils for tolerances and coating thickness
- Legacy aircraft designs (Boeing, Lockheed Martin) remain in decimal-inch/mil system
- Interchangeable parts for decades-old platforms require dimensional consistency
3. Precision machining and manufacturing:
- Tolerances routinely specified in mils (±1 mil, ±5 mil)
- Micrometer readings in decimal inches (thousandths)
- CNC programming often in inches/mils in American shops
4. Coating and painting industries:
- ASTM and SSPC standards specify dry film thickness (DFT) in mils
- Paint thickness gauges calibrated in mils
- Industrial specifications: "8-10 mils total coating system"
5. Plastic film and flexible packaging:
- Film thickness: "6-mil poly sheeting," "4-mil polyester film"
- ASTM standards for plastic film thickness use mils
6. Wire and cable manufacturing:
- American Wire Gauge (AWG) based on diameter in mils
- Insulation thickness specified in mils over conductor
7. Sheet metal fabrication:
- Actual thickness often specified in decimal inches (mils) to avoid gauge confusion
- "0.063″ aluminum" (63 mils) instead of ambiguous "14-gauge"
Why mils persist:
- Billions in tooling and infrastructure calibrated in imperial units
- Legacy designs: Decades of proven engineering in mils cannot be easily converted
- Risk avoidance: Metric/imperial conversion errors are costly and dangerous (Mars Climate Orbiter)
- Supply chain compatibility: Entire ecosystems of suppliers and manufacturers use consistent units
- No economic driver: Purely domestic manufacturing has little incentive to convert
Metric adoption: Global companies (automotive, consumer electronics) increasingly use dual dimensioning (both mils and mm) or shift new designs to metric, but maintenance and support of existing products ensures mils remain relevant for decades.
Conclusion: Mils are actively used, not obsolete, and will remain standard in American manufacturing for the foreseeable future—especially in aerospace, defense, electronics, and precision machining.
What's the difference between a mil and a milliradian?
Completely different units from different measurement domains—they only share a similar name:
Mil (length):
- Unit of length = 0.001 inches (one thousandth of an inch)
- Used in manufacturing, coating thickness, electronics, tolerances
- Example: "The coating is 5 mils thick."
Milliradian (angular measurement):
- Unit of angle = 0.001 radians ≈ 0.0573 degrees
- Used in artillery, ballistics, marksmanship, optics, surveying
- Example: "The rifle scope adjustment is 0.1 milliradian per click."
No conversion between them—they measure fundamentally different things (distance vs. angle).
Confusing terminology: In military and shooting contexts, "mil" is often shorthand for milliradian (angular mil), while in manufacturing, "mil" always means 0.001 inch (linear mil). Context determines meaning.
Additional angular "mil" units (adding to confusion):
- NATO mil (milliradian): 1/1000 radian ≈ 0.0573°
- Swedish/metric mil: 1/6000 of a circle ≈ 0.06° (slightly larger than milliradian)
- Artillery mil (historical): 1/6400 of a circle ≈ 0.05625°
Summary: Unless you're discussing ballistics or optics, "mil" refers to 0.001 inch in American industry and manufacturing.
Conversion Table: Yard to Mil/Thou
| Yard (yd) | Mil/Thou (mil) |
|---|---|
| 0.5 | 18,000 |
| 1 | 36,000 |
| 1.5 | 54,000 |
| 2 | 72,000 |
| 5 | 180,000 |
| 10 | 360,000 |
| 25 | 900,000 |
| 50 | 1,800,000 |
| 100 | 3,600,000 |
| 250 | 9,000,000 |
| 500 | 18,000,000 |
| 1,000 | 36,000,000 |
People Also Ask
How do I convert Yard to Mil/Thou?
To convert Yard to Mil/Thou, enter the value in Yard in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our length converter page to convert between other units in this category.
Learn more →What is the conversion factor from Yard to Mil/Thou?
The conversion factor depends on the specific relationship between Yard and Mil/Thou. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Mil/Thou back to Yard?
Yes! You can easily convert Mil/Thou back to Yard by using the swap button (⇌) in the calculator above, or by visiting our Mil/Thou to Yard converter page. You can also explore other length conversions on our category page.
Learn more →What are common uses for Yard and Mil/Thou?
Yard and Mil/Thou are both standard units used in length measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our length converter for more conversion options.
For more length conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
📚 How to Convert Units
Step-by-step guide to unit conversion with practical examples.
🔢 Conversion Formulas
Essential formulas for length and other conversions.
⚖️ Metric vs Imperial
Understand the differences between measurement systems.
⚠️ Common Mistakes
Learn about frequent errors and how to avoid them.
All Length Conversions
Other Length Units and Conversions
Explore other length units and their conversion options:
- Meter (m) • Yard to Meter
- Kilometer (km) • Yard to Kilometer
- Hectometer (hm) • Yard to Hectometer
- Decimeter (dm) • Yard to Decimeter
- Centimeter (cm) • Yard to Centimeter
- Millimeter (mm) • Yard to Millimeter
- Inch (in) • Yard to Inch
- Foot (ft) • Yard to Foot
- Mile (mi) • Yard to Mile
- Nautical Mile (NM) • Yard to Nautical Mile
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Official US standards for length measurements
Bureau International des Poids et Mesures — International System of Units official documentation
Last verified: December 3, 2025