Convert Millimeter to Chain
Convert millimeters to chains instantly. 1 millimeter = 4.97097e-5 chain — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Chain to Millimeter converter for the reverse conversion.
Units explained
Millimeter
A millimeter is a metric unit of length equal to one thousandth of a meter (1/1000 m). It is the standard small-scale unit in the SI system and is widely used wherever sub-centimeter precision matters.
The millimeter was defined alongside the meter when France adopted the metric system in 1795, using the standard SI prefix milli- (from Latin mille, "thousand") to denote one-thousandth.
Millimeters are used in engineering drawings, machining, manufacturing, paper sizes, rainfall measurement, and any context where dimensions below one centimeter need to be specified clearly. Most rulers worldwide are marked in millimeters.
Adopted in 1795 in France as part of the original metric system; standardized internationally by the Metre Convention in 1875 and confirmed in the SI in 1960.
Chain
A chain is an Imperial unit of length equal to 66 feet (20.1168 m), or exactly 4 rods or 100 links. It is the central unit in the Gunter chain-based land-survey system.
Defined by Edmund Gunter in 1620 specifically to make land-area arithmetic easy: 10 square chains = 1 acre exactly. The 66-foot length and 100-link subdivision were chosen so chain measurements could be added decimally.
Chains are the fundamental unit of legacy US public land surveys (the entire US township-and-range system uses chains). Modern survey work generally uses meters or feet, but legacy deeds remain in chains.
Invented by Edmund Gunter in 1620; standardised throughout English and American land survey; became exact via the 1959 International Yard and Pound Agreement.
Millimeter to Chain conversion formula
The relationship between millimeters and chains:
To convert millimeters to chains, multiply the value in millimeters by 4.97097e-5. To reverse, multiply chains by 20116.8.
How to use this converter
Type a value into the calculator. The result in chains updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Chain to Millimeter converter for the reverse direction.
Step-by-step: convert millimeters to chains
- Write down the value in millimeters (mm).
- Multiply that value by the factor 4.97097e-5.
- The product is the equivalent value in chains (ch).
- To reverse, multiply the chain value by 20116.8.
Worked examples
Example 1 — Convert 1 mm to ch:
1 × 4.97097e-5 = 4.97097e-5 ch
Example 2 — Convert 100 mm to ch:
100 × 4.97097e-5 = 0.0049709695 ch
Real-world example — Hardware-scale dimensions
A 10-millimeter fastener or component is about as long as a thumbnail. Mechanics and DIY enthusiasts convert between millimeters and chains daily when mixing metric and imperial tools.
10 mm × 4.97097e-5 = 0.000497097 ch
Real-world example — Postcard and small-object dimensions
A postcard is about 5 millimeters wide. Converting to chains is essential for international postal addressing forms that ask for dimensions in different units across countries.
5 mm × 4.97097e-5 = 0.0002485485 ch
Real-world example — Ruler-scale measurements
A 30-millimeter school ruler converts cleanly to chains — useful when buying a desk accessory from a retailer whose product specs use a different unit.
30 mm × 4.97097e-5 = 0.0014912909 ch
Millimeter to Chain conversion table
Standard reference values for converting millimeters to chains:
| Millimeter [mm] | Chain [ch] |
|---|---|
| 0.01 | 4.97097e-7 |
| 0.1 | 4.97097e-6 |
| 1 | 4.97097e-5 |
| 2 | 9.941939e-5 |
| 3 | 0.0001491291 |
| 4 | 0.0001988388 |
| 5 | 0.0002485485 |
| 10 | 0.000497097 |
| 20 | 0.0009941939 |
| 30 | 0.0014912909 |
| 40 | 0.0019883878 |
| 50 | 0.0024854848 |
| 100 | 0.0049709695 |
| 500 | 0.0248548477 |
| 1000 | 0.0497096954 |
Frequently asked questions
How many chains is 1 millimeter?
How do I convert millimeters to chains?
How do I convert chains back to millimeters?
How many chains is 100 millimeters?
Popular length unit conversions
Convert Millimeter to other length units
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Metric / SI (17 units)
Imperial / US Customary (27 units)
Nautical (1 units)
Astronomical (9 units)
Atomic / Physics (6 units)
Typographic (3 units)
Sources & references
Conversion factor (1 mm = 4.97097e-5 ch) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.