Convert Chain to Millimeter
Convert chains to millimeters instantly. 1 chain = 20116.8 millimeter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Millimeter to Chain converter for the reverse conversion.
Units explained
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
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 to Millimeter conversion formula
The relationship between chains and millimeters:
To convert chains to millimeters, multiply the value in chains by 20116.8. To reverse, multiply millimeters by 4.97097e-5.
How to use this converter
Type a value into the calculator. The result in millimeters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Millimeter to Chain converter for the reverse direction.
Step-by-step: convert chains to millimeters
- Write down the value in chains (ch).
- Multiply that value by the factor 20116.8.
- The product is the equivalent value in millimeters (mm).
- To reverse, multiply the millimeter value by 4.97097e-5.
Worked examples
Example 1 — Convert 1 ch to mm:
1 × 20116.8 = 20116.8 mm
Example 2 — Convert 100 ch to mm:
100 × 20116.8 = 2011680 mm
Chain to Millimeter conversion table
Standard reference values for converting chains to millimeters:
| Chain [ch] | Millimeter [mm] |
|---|---|
| 0.01 | 201.168 |
| 0.1 | 2011.68 |
| 1 | 20116.8 |
| 2 | 40233.6 |
| 3 | 60350.4 |
| 4 | 80467.2 |
| 5 | 100584 |
| 10 | 201168 |
| 20 | 402336 |
| 30 | 603504 |
| 40 | 804672 |
| 50 | 1005840 |
| 100 | 2011680 |
| 500 | 1.00584e+7 |
| 1000 | 2.01168e+7 |
Frequently asked questions
How many millimeters is 1 chain?
How do I convert chains to millimeters?
How do I convert millimeters back to chains?
How many millimeters is 100 chains?
Popular length unit conversions
Convert Chain to other length units
Show all Chain conversions
Metric / SI (4 units)
Imperial / US Customary (26 units)
Sources & references
Conversion factor (1 ch = 20116.8 mm) 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.