Bolt to Millimeter Converter
Convert bolts to millimeters with our free online length converter.
Quick Answer
1 Bolt = 30480 millimeters
Formula: Bolt × conversion factor = Millimeter
Use the calculator below for instant, accurate conversions.
Our Accuracy Guarantee
All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.
Bolt to Millimeter Calculator
How to Use the Bolt to Millimeter Calculator:
- Enter the value you want to convert in the 'From' field (Bolt).
- The converted value in Millimeter 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 Bolt to Millimeter: Step-by-Step Guide
Converting Bolt to Millimeter involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Bolt = 3.0480e+4 millimetersExample Calculation:
Convert 10 bolts: 10 × 3.0480e+4 = 3.0480e+5 millimeters
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 Bolt and a Millimeter?
A Bolt is a commercial unit of length primarily used for measuring rolls of cloth or fabric. Unlike standardized units like the meter or yard, the length of a bolt is not fixed and can vary significantly depending on the type of material, the manufacturer, the country of origin, and trade customs.
Common lengths often associated with a bolt include:
- 40 yards (approximately 36.58 meters) - Frequently cited, especially for cottons and silks in the US.
- 100 yards (approximately 91.44 meters) - Often used for heavier fabrics like canvas.
- Other lengths such as 30, 50, 60, or 120 yards may also be encountered.
The bolt represents a quantity convenient for wholesale trade, manufacturing, and inventory management rather than a precise scientific measurement.
The millimeter (symbol: mm) is a unit of length in the metric system equal to one-thousandth of a meter (1/1,000 m) or one-tenth of a centimeter (1/10 cm). It is used for precise measurements in engineering, manufacturing, and everyday applications.
Key relationships:
- 1 millimeter = 0.001 meters (m)
- 1 millimeter = 0.1 centimeters (cm)
- 10 millimeters = 1 centimeter
- 1,000 millimeters = 1 meter
- 1 millimeter ≈ 0.03937 inches (about 1/25th inch)
- 25.4 millimeters = 1 inch (exactly)
The prefix "milli-":
- From Latin "mille" meaning "thousand"
- SI prefix denoting 10⁻³ (one-thousandth)
- Also used in: milligram (mg), milliliter (mL), millisecond (ms)
Visual perspective (how big is it?):
- 1 mm = Thickness of a credit card
- 2 mm = Thickness of a US dime
- 5 mm = Thickness of a pencil lead (mechanical)
- 10 mm = Width of an adult fingernail
- 25.4 mm = Exactly one inch
Convert between length units: mm converter
Note: The Bolt is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Millimeter belongs to the metric (SI) system.
History of the Bolt and Millimeter
The concept of the bolt emerged from the practical needs of the textile industry. As cloth production scaled up, manufacturers and merchants needed a standardized way to handle, store, and trade large quantities of fabric. Winding cloth onto a roll or board (the "bolt") provided a convenient package.
The length associated with a bolt likely developed through trade customs specific to different types of fabric and regions. There was never a universal legal standard defining its length, leading to the wide variations seen historically and currently. While retail sales shifted towards measurement by the yard or meter, the bolt remained a useful unit in wholesale and industrial contexts. Even with the global adoption of the metric system, the term "bolt" persists in the textile trade as a reference to a full roll of fabric, though the exact length is usually specified separately in yards or meters.
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Metric System Origins: The millimeter was defined as a subunit of the meter when the metric system was established in France during the late 18th century (1790s). As measurement standardization progressed, the need for decimal subdivisions of the meter became clear.
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Industrial Revolution: The millimeter became essential during the 19th century Industrial Revolution as:
- Precision machining required fine tolerances
- Interchangeable parts manufacturing emerged
- Engineering drawings needed standard units
- Technical specifications became international
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Engineering Adoption: By the mid-19th century, engineers and machinists worldwide adopted millimeters as the standard for:
- Machine tool specifications
- Tolerance requirements (±0.1 mm common)
- Technical drawing dimensions
- Quality control measurements
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Scientific Standardization: The millimeter became standard in scientific research for:
- Laboratory equipment calibration
- Microscopy measurements
- Specimen documentation
- Experimental apparatus dimensions
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SI Formalization: When the International System of Units (SI) was established in 1960, the millimeter was confirmed as an official subdivision of the meter, forming part of the coherent decimal system.
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Modern Manufacturing: The 20th century saw millimeters become universal in:
- Automotive engineering specifications
- Electronics manufacturing (PCB design)
- Aerospace tolerances
- Medical device specifications
- Consumer product dimensions
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Global Standard: Today, millimeters are the primary unit for precision measurements in virtually every country except the United States (which uses both mm and inches). Even in the US, many technical fields have adopted millimeters as standard.
Common Uses and Applications: bolts vs millimeters
Explore the typical applications for both Bolt (imperial/US) and Millimeter (metric) to understand their common contexts.
Common Uses for bolts
The bolt is almost exclusively used within the textile industry:
- Wholesale Trade: Fabric manufacturers sell cloth to distributors or large buyers in bolts.
- Manufacturing: Clothing and upholstery manufacturers purchase fabric by the bolt for production runs.
- Inventory Management: Textile mills, warehouses, and large retailers manage stock using bolts as units.
- Industrial Fabrics: Suppliers of canvas, vinyl, and other industrial textiles often sell material by the bolt.
It is generally not used for retail sales to consumers, where fabric is typically measured and cut to specific lengths (yards or meters) from the bolt.
When to Use millimeters
The millimeter is the standard unit for precise measurements across multiple fields:
Engineering & Machining
Precise measurement requirements for manufacturing, quality control, and technical specifications. Essential for maintaining tolerances in mechanical parts.
Why millimeters in engineering:
- Decimal system (easy calculations)
- International standard (ISO)
- Suitable precision range
- Compatible with CNC machinery
- Standard drawing units
Applications:
- Machine tool specifications
- Part tolerances (±0.05 mm common)
- Technical drawing dimensions
- CAD/CAM software units
- Quality inspection reports
Convert for technical work: mm to inches | mm to cm
Technical Design & Drafting
Standard measurement unit for architectural, mechanical, and technical drawings worldwide.
Drawing Standards:
- ISO standards use millimeters
- Engineering drawings in mm
- Architecture plans (many countries)
- Product design specifications
- Patent drawings (international)
Why mm for drawings:
- Eliminates fractions (unlike inches)
- Scales easily (1:10, 1:100, etc.)
- International communication
- CAD software standard
Electronics & PCB Design
Measuring component sizes, trace widths, and circuit board dimensions in electronic manufacturing.
PCB Design:
- Trace width: 0.25-1 mm
- Component footprints: mm specifications
- Hole diameters: 0.6-1.2 mm
- Board thickness: 1.6 mm standard
- Component spacing: mm grid
Component Specs:
- All modern ICs specified in mm
- Resistor/capacitor sizes (mm codes)
- Connector dimensions
- Display module sizes
Meteorology & Climate
Measuring rainfall amounts with precision, essential for weather forecasting, agriculture, and climate research.
Rain Gauges:
- Standard measurement unit worldwide
- Collected in graduated cylinders (mm scale)
- Automated weather stations use mm
- Historical records in mm
- Climate data standardized
Importance:
- Drought assessment
- Flood prediction
- Agricultural planning
- Water resource management
- Climate change tracking
Use our mm converter for scientific calculations.
Manufacturing & Quality Control
Inspecting product dimensions and ensuring parts meet specifications within required tolerances.
QC Measurements:
- Caliper readings in mm
- Micrometer measurements
- Coordinate measuring machines (CMM)
- Surface profile measurements
- Dimensional inspection reports
Industries:
- Automotive parts
- Aerospace components
- Medical devices
- Consumer electronics
- Precision instruments
Jewelry & Watchmaking
Specifying sizes of gems, watch cases, and jewelry components with precision.
Why jewelers use mm:
- International gem standard
- Precise size communication
- Watch industry standard
- Setting specifications
- Customer communication
Measurements:
- Gemstone dimensions
- Ring widths and thicknesses
- Watch case diameters
- Bracelet link sizes
- Clasp dimensions
Medical Measurements
Documenting precise measurements in diagnostics, surgery planning, and treatment monitoring.
Clinical Uses:
- Imaging measurements (CT, MRI, X-ray)
- Tumor size tracking
- Surgical planning
- Needle specifications
- Medical device dimensions
Why mm in medicine:
- International standard
- Appropriate precision
- Imaging system default
- Research compatibility
- Treatment standardization
Additional Unit Information
About Bolt (bolt)
How long is a bolt of cloth?
There is no single standard length. It depends heavily on the fabric type and manufacturer. Common lengths include:
- 40 yards (~36.58 m)
- 100 yards (~91.44 m)
- Other lengths like 30, 50, 60, or 120 yards are also possible. Always check the specific product information for the actual length of a particular bolt.
How many yards are in a bolt?
Commonly 40 yards or 100 yards, but this is highly variable.
How many meters are in a bolt?
Based on common yard lengths:
- A 40-yard bolt is approximately 36.58 meters.
- A 100-yard bolt is approximately 91.44 meters.
Is the bolt a standardized unit?
No, it is not a standardized unit of length like the yard or meter. It's a commercial trade unit whose length varies.
Is the bolt still used today?
Yes, the term "bolt" is still widely used in the wholesale textile industry and manufacturing contexts to refer to a full roll of fabric, although the precise length is usually specified in yards or meters.
Is this related to the fastener "bolt"?
No, the bolt unit for cloth is completely unrelated to the metal fastener known as a bolt. They share the same name but have entirely different meanings and origins.
About Millimeter (mm)
How many millimeters are in a centimeter?
There are exactly 10 millimeters (mm) in 1 centimeter (cm).
Conversion:
- 1 cm = 10 mm
- To convert cm to mm: multiply by 10
- To convert mm to cm: divide by 10
Examples:
- 5 cm = 50 mm
- 2.5 cm = 25 mm
- 75 mm = 7.5 cm
Memory aid: "Centi-" means 1/100 meter, "milli-" means 1/1,000 meter, so 10 mm = 1 cm.
Use our cm to mm converter for instant conversions.
How many millimeters are in a meter?
There are exactly 1,000 millimeters (mm) in 1 meter (m).
Conversion:
- 1 m = 1,000 mm
- To convert m to mm: multiply by 1,000
- To convert mm to m: divide by 1,000
Examples:
- 0.5 m = 500 mm
- 1.5 m = 1,500 mm
- 2,750 mm = 2.75 m
Remember: "Milli-" means one-thousandth, so it takes 1,000 mm to make 1 meter.
Convert: mm to meters | meters to mm
What does 'milli' mean in millimeter?
The prefix 'milli-' denotes one-thousandth (1/1,000).
Meaning:
- Comes from Latin "mille" meaning "thousand"
- In metric system: milli- = 10⁻³ = 1/1,000
- 1 millimeter = 1/1,000 of a meter = 0.001 m
Other "milli-" units:
- Milligram (mg) = 1/1,000 gram
- Milliliter (mL) = 1/1,000 liter
- Millisecond (ms) = 1/1,000 second
- Milliamp (mA) = 1/1,000 ampere
Pattern: Always divide by 1,000 to get the base unit.
How thick is 1 millimeter?
1 millimeter is very thin - about the thickness of:
Common objects:
- Credit card: 0.76 mm (slightly thinner)
- US dime: 1.35 mm (slightly thicker)
- 10 sheets of paper: ~1 mm
- Paperclip wire: ~1 mm diameter
- Mechanical pencil lead (0.7mm): Slightly thinner
Visual comparison:
- Thinner than a US penny (1.55 mm)
- About 1/25th of an inch (0.04 inches)
- 10 millimeters = 1 cm = width of fingernail
To visualize: Look at the edge of a credit card - that's less than 1 mm.
How many mm in an inch?
1 inch = 25.4 millimeters exactly (by international agreement).
This is a defined conversion (not an approximation):
- 1 inch ≡ 25.4 mm (exact)
- 1 mm = 1/25.4 inch ≈ 0.03937 inches
Common conversions:
- 1 inch = 25.4 mm
- 2 inches = 50.8 mm
- 3 inches = 76.2 mm
- 4 inches = 101.6 mm
- 12 inches (1 foot) = 304.8 mm
Reverse examples:
- 10 mm ≈ 0.394 inches
- 25 mm ≈ 0.984 inches (almost 1 inch)
- 50 mm ≈ 1.969 inches (almost 2 inches)
Memory trick: 25 mm is almost 1 inch (close enough for quick estimates).
Use our inch to mm converter for precise conversions.
What is 10mm in real life?
10 millimeters = 1 centimeter - about the width of an adult fingernail.
Common 10mm objects:
- Fingernail width (adult index finger)
- AA battery diameter: 14 mm (close)
- Small marble: ~10-15 mm diameter
- M10 bolt diameter: 10 mm
- Thick cardboard: ~10 mm
Comparisons:
- Just under 0.4 inches (0.394 inches exactly)
- Thickness of 100 sheets of paper
- About 3/8 inch (slightly larger)
In measurements:
- Camera/phone thickness: Often 7-10 mm
- Watch case thickness: Often 10-12 mm
- Pencil diameter: ~7-8 mm (10mm would be thick)
How do you read a metric ruler?
Metric rulers are divided into centimeters (cm) and millimeters (mm):
Reading steps:
- Large numbers: Centimeters (0, 1, 2, 3...)
- Long lines: Each centimeter mark
- Short lines: Millimeters (10 per cm)
- Count: From zero to your measurement point
Example reading:
- Between 3 and 4 cm, at the 7th small line = 3.7 cm or 37 mm
- At the 15th cm mark = 15 cm or 150 mm
Tips:
- 10 small marks = 1 cm
- Each small mark = 1 mm
- Halfway between cm marks = 5 mm
- Read to nearest 0.5 mm for precision
Reporting:
- Small objects: Use mm (e.g., "15 mm")
- Larger objects: Use cm (e.g., "15.5 cm")
- Both are correct, choose clearer one
What tools measure millimeters?
Many tools measure in millimeters:
Hand Tools:
- Metric ruler: Basic measurement to 1 mm
- Metric tape measure: Construction/carpentry
- Caliper: Precision to 0.01 mm (digital/vernier)
- Micrometer: Very precise, to 0.001 mm
- Depth gauge: Measuring depths and heights
Digital Tools:
- Digital caliper: Easy reading, 0.01 mm precision
- Laser distance meter: Millimeter accuracy
- Height gauge: Vertical measurements
- Coordinate measuring machine (CMM): Industrial precision
Specialized Tools:
- Feeler gauge: Thin strips in mm thicknesses
- Thread gauge: Checking thread pitch (mm)
- Bore gauge: Internal diameter measurement
- Pin gauge: Precision hole measurement
Which to use:
- Ruler: General purpose (±0.5 mm)
- Caliper: Precision work (±0.01 mm)
- Micrometer: Very tight tolerances (±0.001 mm)
Is mm smaller than cm?
Yes, millimeters (mm) are smaller than centimeters (cm).
Relationship:
- 1 cm = 10 mm
- 1 mm = 0.1 cm
- Millimeter is 10 times smaller than centimeter
Scale comparison:
- Largest: meter (m)
- Middle: centimeter (cm) = 1/100 m
- Smallest: millimeter (mm) = 1/1,000 m
Visual:
- Width of fingernail: 1 cm = 10 mm
- Thickness of dime: 1.35 mm (can't easily express in cm)
When to use each:
- Use mm: Small, precise measurements (< 100 mm)
- Use cm: Medium measurements (1-100 cm)
- Use m: Large measurements (> 1 meter)
Example:
- Pencil length: 19 cm or 190 mm (19 cm clearer)
- Wire diameter: 2 mm (not 0.2 cm - awkward)
How much rain is 1mm?
1 millimeter of rain means 1 mm depth of water would cover a flat surface if none drained away.
What it means:
- 1 mm rain = 1 liter per square meter of water
- Light drizzle might produce 1-2 mm/hour
- Barely enough to wet the ground thoroughly
Rain intensity scale:
- Trace-1 mm: Very light drizzle
- 1-2 mm: Light rain
- 2-5 mm: Light to moderate rain
- 5-10 mm: Moderate rain
- 10-20 mm: Heavy rain
- 20-50 mm: Very heavy rain
- >50 mm: Extreme rainfall (per hour)
Practical impact:
- 1 mm: Barely wets surfaces
- 10 mm: Significant watering
- 25 mm: Heavy rain event
- 100 mm: Major storm (in 24 hours)
Measurement:
- Rain gauge collects water
- Depth measured in mm
- Standard worldwide for weather reporting
Conversion Table: Bolt to Millimeter
| Bolt (bolt) | Millimeter (mm) |
|---|---|
| 0.5 | 15,240 |
| 1 | 30,480 |
| 1.5 | 45,720 |
| 2 | 60,960 |
| 5 | 152,400 |
| 10 | 304,800 |
| 25 | 762,000 |
| 50 | 1,524,000 |
| 100 | 3,048,000 |
| 250 | 7,620,000 |
| 500 | 15,240,000 |
| 1,000 | 30,480,000 |
People Also Ask
How do I convert Bolt to Millimeter?
To convert Bolt to Millimeter, enter the value in Bolt 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 Bolt to Millimeter?
The conversion factor depends on the specific relationship between Bolt and Millimeter. 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 Millimeter back to Bolt?
Yes! You can easily convert Millimeter back to Bolt by using the swap button (⇌) in the calculator above, or by visiting our Millimeter to Bolt converter page. You can also explore other length conversions on our category page.
Learn more →What are common uses for Bolt and Millimeter?
Bolt and Millimeter 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) • Bolt to Meter
- Kilometer (km) • Bolt to Kilometer
- Hectometer (hm) • Bolt to Hectometer
- Decimeter (dm) • Bolt to Decimeter
- Centimeter (cm) • Bolt to Centimeter
- Inch (in) • Bolt to Inch
- Foot (ft) • Bolt to Foot
- Yard (yd) • Bolt to Yard
- Mile (mi) • Bolt to Mile
- Nautical Mile (NM) • Bolt 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: February 19, 2026