Millimeter to Arpent Converter

Convert millimeters to arpents with our free online length converter.

Quick Answer

1 Millimeter = 0.0000171 arpents

Formula: Millimeter × conversion factor = Arpent

Use the calculator below for instant, accurate conversions.

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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.

Last verified: February 2026|Reviewed by: Sam Mathew, Software Engineer

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How to Use the Millimeter to Arpent Calculator:

Enter the value you want to convert in the 'From' field (Millimeter).
The converted value in Arpent 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 Millimeter to Arpent: Step-by-Step Guide

Converting Millimeter to Arpent involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Millimeter = 1.7102e-5 arpents

Example Calculation:

Convert 10 millimeters: 10 × 1.7102e-5 = 0.000171025 arpents

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.

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What is a Millimeter and a Arpent?

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

The Arpent is a historical French unit used primarily for measuring land area, but also sometimes used as a unit of length. As a unit of length, the arpent typically referred to the side length of a square arpent of land.

Its precise length varied significantly by region and time period in France and its colonies. A commonly cited value, particularly associated with the arpent de Paris, is based on 180 French feet (pieds du Roi), which equates to approximately:

58.47 meters (m)
191.8 feet (ft)

Other variations existed, such as the arpent commun (based on 200 French feet, ~64.97 m) and the arpent d'ordonnance (based on 220 French feet, ~71.47 m).

Note: The Millimeter is part of the metric (SI) system, primarily used globally in science and trade. The Arpent belongs to the imperial/US customary system.

History of the Millimeter and Arpent

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.
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
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
Scientific Standardization: The millimeter became standard in scientific research for:
- Laboratory equipment calibration
- Microscopy measurements
- Specimen documentation
- Experimental apparatus dimensions
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.
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
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.

The term "arpent" likely derives from the Gaulish arepennis, meaning "end of a field," suggesting its origins relate to agricultural land measurement, possibly representing the amount of land that could be plowed in a day. It became a fundamental unit for land surveying in France during the medieval period and remained in use until the adoption of the metric system following the French Revolution.

Regional Variations: Before standardization efforts, the length (and thus area) of the arpent varied considerably across different regions of France. Key variations included:
- Arpent de Paris: Based on a perche (rod) of 18 pieds du Roi (French feet), with the linear arpent (side of the square) being 10 perches, totaling 180 pieds (~58.47 m). The area was 32,400 square pieds.
- Arpent Commun: Based on a perche of 20 pieds, linear arpent of 200 pieds (~64.97 m). Area: 40,000 square pieds.
- Arpent d'Ordonnance (or Arpent des Eaux et Forêts): Based on a perche of 22 pieds, linear arpent of 220 pieds (~71.47 m). Area: 48,400 square pieds. Used primarily for royal forests.
Colonial Usage: The arpent was exported to French colonies, notably:
- New France (Quebec, Canada): The arpent de Paris became the standard for land grants along the St. Lawrence River, shaping the characteristic long, narrow farm plots (rangs).
- Louisiana (USA): The French arpent (usually the arpent de Paris) was used for land measurement before and sometimes after the Louisiana Purchase. Its legacy persists in land titles and some place names.
Metrication: The metric system officially replaced the arpent and other traditional units in France in the late 18th and early 19th centuries, though its use lingered in practice and historical records.

Common Uses and Applications: millimeters vs arpents

Explore the typical applications for both Millimeter (metric) and Arpent (imperial/US) to understand their common contexts.

Common Uses for 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

When to Use arpents

The Arpent (both linear and area) is now largely obsolete for practical measurement but remains historically significant:

Historical Land Surveys: Essential for interpreting old maps, deeds, and land grants in France, Quebec, Louisiana, and other areas formerly under French control (e.g., parts of the US Midwest like Missouri, Illinois, Indiana).
Legal Context: Land descriptions in some regions may still reference original measurements in arpents, requiring conversion for modern understanding.
Historical Research: Understanding the arpent is crucial for historians studying agriculture, settlement patterns, and land tenure systems in French history and its colonial contexts.
Unit of Area: While this page focuses on the length, the arpent is more commonly known and encountered as a unit of area (the square arpent).

Additional Unit Information

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

About Arpent (arpent)

Is the Arpent a unit of length or area?

The Arpent is primarily known as a unit of area, representing a specific parcel of land. However, a linear arpent also exists, defined as the side length of a square whose area is one arpent. This page focuses on the linear arpent. The relationship is direct: Area Arpent = (Linear Arpent)². Because the linear arpent varied, the area also varied.

Where is the Arpent still relevant?

The Arpent is not used for everyday measurements today. Its relevance is almost entirely historical and legal:

Quebec (Canada): Crucial for understanding historical land division and property lines, especially the seigneurial system.
Louisiana (USA): Important for interpreting land titles dating back to the French colonial period.
France: Relevant for historical studies and understanding old documents.
Other former French territories: May appear in historical records (e.g., Mauritius, parts of the US Midwest).

How long is a linear Arpent?

There is no single value, as it varied regionally. Common historical values include:

Arpent de Paris: ~180 French feet ≈ 58.47 meters ≈ 191.8 feet (Most common in Quebec & Louisiana)
Arpent Commun: ~200 French feet ≈ 64.97 meters ≈ 213.2 feet
Arpent d'Ordonnance: ~220 French feet ≈ 71.47 meters ≈ 234.5 feet (Note: The French foot, pied du Roi, was slightly longer than the English foot, approx. 32.48 cm or 12.79 inches).

How does the linear Arpent compare to a Meter or Foot?

The most common linear arpent (~58.47 m) is significantly longer than a meter. (1 Arpent ≈ 58.47 m)
It is also much longer than a foot. (1 Arpent ≈ 191.8 ft)

Is the Arpent an SI unit?

No, the Arpent is not an SI unit. It is a traditional unit from the French system of measurements. The SI base unit for length is the meter (m), and the SI unit for area is the square meter (m²).

Conversion Table: Millimeter to Arpent

Millimeter (mm)	Arpent (arpent)
0.5	0
1	0
1.5	0
2	0
5	0
10	0
25	0
50	0.001
100	0.002
250	0.004
500	0.009
1,000	0.017

How do I convert Millimeter to Arpent?

To convert Millimeter to Arpent, enter the value in Millimeter 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.

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What is the conversion factor from Millimeter to Arpent?

The conversion factor depends on the specific relationship between Millimeter and Arpent. 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 Arpent back to Millimeter?

Yes! You can easily convert Arpent back to Millimeter by using the swap button (⇌) in the calculator above, or by visiting our Arpent to Millimeter converter page. You can also explore other length conversions on our category page.

Learn more →

What are common uses for Millimeter and Arpent?

Millimeter and Arpent 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

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All Length Conversions

Meter to Kilometer Meter to Hectometer Meter to Decimeter Meter to Centimeter Meter to Millimeter Meter to Inch Meter to Foot Meter to Yard Meter to Mile Meter to Nautical Mile Meter to Micrometer Meter to Nanometer Meter to Light Year Meter to Astronomical Unit Meter to Parsec Meter to Angstrom Meter to Point (Typography)Meter to Mil/Thou Meter to Fathom Meter to Furlong Meter to Link (Gunter's)Meter to Pace Meter to Span Meter to Digit Meter to Cable Length Meter to Ell Meter to Finger Meter to Roman Mile Meter to Stadion Meter to Chi (Chinese)Meter to Shaku (Japanese)Meter to Li (Chinese)Meter to Toise Meter to Bolt Meter to Rope Meter to Smoot Meter to Sajene Meter to Ken Meter to Wa Meter to Vara Meter to Aln Meter to Cubit (Royal/Egyptian)Meter to Versta Meter to Arpent Meter to Ri (Japanese)Meter to Klafter Meter to Yojana Meter to Skein Kilometer to Meter Kilometer to Hectometer Kilometer to Decimeter Kilometer to Centimeter Kilometer to Millimeter Kilometer to Inch Kilometer to Foot Kilometer to Yard Kilometer to Mile Kilometer to Nautical Mile Kilometer to Micrometer Kilometer to Nanometer Kilometer to Light Year Kilometer to Astronomical Unit Kilometer to Parsec Kilometer to Angstrom Kilometer to Point (Typography)Kilometer to Mil/Thou Kilometer to Fathom Kilometer to Furlong Kilometer to Link (Gunter's)Kilometer to Pace Kilometer to Span Kilometer to Digit Kilometer to Cable Length Kilometer to Ell Kilometer to Finger Kilometer to Roman Mile Kilometer to Stadion Kilometer to Chi (Chinese)Kilometer to Shaku (Japanese)Kilometer to Li (Chinese)Kilometer to Toise Kilometer to Bolt Kilometer to Rope Kilometer to Smoot Kilometer to Sajene Kilometer to Ken Kilometer to Wa Kilometer to Vara Kilometer to Aln Kilometer to Cubit (Royal/Egyptian)Kilometer to Versta Kilometer to Arpent Kilometer to Ri (Japanese)Kilometer to Klafter Kilometer to Yojana Kilometer to Skein Hectometer to Meter Hectometer to Kilometer Hectometer to Decimeter Hectometer to Centimeter Hectometer to Millimeter Hectometer to Inch Hectometer to Foot Hectometer to Yard Hectometer to Mile Hectometer to Nautical Mile Hectometer to Micrometer Hectometer to Nanometer Hectometer to Light Year Hectometer to Astronomical Unit Hectometer to Parsec Hectometer to Angstrom Hectometer to Point (Typography)Hectometer to Mil/Thou Hectometer to Fathom Hectometer to Furlong Hectometer to Link (Gunter's)Hectometer to Pace Hectometer to Span Hectometer to Digit

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Other Length Units and Conversions

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Meter (m) • Millimeter to Meter
Kilometer (km) • Millimeter to Kilometer
Hectometer (hm) • Millimeter to Hectometer
Decimeter (dm) • Millimeter to Decimeter
Centimeter (cm) • Millimeter to Centimeter
Inch (in) • Millimeter to Inch
Foot (ft) • Millimeter to Foot
Yard (yd) • Millimeter to Yard
Mile (mi) • Millimeter to Mile
Nautical Mile (NM) • Millimeter to Nautical Mile

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Guide for the Use of SI

National Institute of Standards and Technology — Official US standards for length measurements

SI Brochure

Bureau International des Poids et Mesures — International System of Units official documentation

Last verified: February 19, 2026