# Chains to Millimeters (ch to mm)

Source: https://www.unitconvertercalculator.com/length/chains-to-millimeters/

**1 ch = 20116.8 mm**

One chain equals exactly 20,116.8 millimeters (about 20.1 meters). This conversion connects the historical land surveying chain with the modern precision unit used in engineering and manufacturing. Converting chains to millimeters is occasionally needed when old survey measurements must be expressed in fine metric detail.

## Formula

Convert Chains to Millimeters

## Conversion Table

| Chains (ch) | Millimeters (mm) |
|---|---|
| 0.01 ch | 201.168 mm |
| 0.05 ch | 1005.84 mm |
| 0.1 ch | 2011.68 mm |
| 0.25 ch | 5029.2 mm |
| 0.5 ch | 10058.4 mm |
| 1 ch | 20116.8 mm |
| 2 ch | 40233.6 mm |
| 5 ch | 100584 mm |
| 10 ch | 201168 mm |
| 20 ch | 402336 mm |
| 40 ch | 804672 mm |
| 80 ch | 1609344 mm |
| 100 ch | 2011680 mm |

## Units

### Chain (ch)

Exactly 66 feet or 4 rods (20.1168 m). Invented by Edmund Gunter for land surveying. 80 chains make one mile. Still used in US public land surveys.

### Millimeter (mm)

A metric unit of length equal to one thousandth of a meter. Used in engineering, manufacturing, and precise measurements.

## Background

A cricket pitch (1 chain) is 20,116.8 mm. One link (1/100 of a chain) is 201.168 mm, or about 7.92 inches. When restoring historical boundary markers to millimeter precision, this conversion becomes relevant. Most practical applications would use meters rather than millimeters for chain-scale distances.

## Good to Know

Modern surveying uses millimeter-precision GPS and total stations, but the boundaries they measure were often originally set in chains and links. The conversion from 17th-century chains to 21st-century millimeters bridges 400 years of measurement technology.

## FAQ

### How many millimeters are in 1 chain?

One chain equals exactly 20,116.8 millimeters. Since 1 chain = 20.1168 meters and 1 meter = 1,000 mm, multiply 20.1168 by 1,000.

### How do I convert chains to millimeters?

Multiply the number of chains by 20,116.8. For example, 3 chains = 3 x 20,116.8 = 60,350.4 mm.

### When would I need millimeter precision for chains?

When placing boundary markers or monuments with surveying instruments that read in millimeters. Modern total stations and GPS units output in meters/millimeters, so old chain measurements need conversion to this precision level.

## Non-Frequently Asked Questions

### How many millimeters of rain does a chain of road collect?

A chain is 20,116.8 mm long. One millimeter of rain on a 1-chain road that is 4 meters wide covers 20,116.8 x 4,000 = 80.5 million square millimeters, or 80.5 liters of water. Even a light drizzle deposits serious water on a chain of road.

### Is a millimeter the smallest useful fraction of a chain?

For surveying, yes. A chain measured to the nearest millimeter (0.005% precision) would satisfy any modern land survey. Old surveyors working with physical chains were lucky to get within 10 mm (half an inch) accuracy.

### Can I buy a chain-length of wire at a hardware store?

Wire is sold in meters or feet, not chains. A chain-length (20.1168 m) of standard copper wire costs about 3 euros. The hardware store clerk will not know what a chain is, but they can cut 20.12 meters without blinking.

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## See Also

- [Millimeters to Chains](https://www.unitconvertercalculator.com/length/millimeters-to-chains/)