Trackside Prints

Miles and chains converter

Type a mileage the railway way, miles then chains, and get it in kilometres, metres and yards. Add a second mileage for the distance between them, or turn kilometres back into miles and chains.

Convert a mileage

12m 34ch = 19.996 km

12 miles 34 chains is 994 chains, 21,868 yards, 19,996.1 metres, or 12.425 miles as a decimal.

The view from a modern train cab: the control desk, the windscreen, and a straight line running to a low sun over farmland
Miles ahead, counted in chains.

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How to use it

Write the miles, a dot, then the chains: 12.34 means 12 miles and 34 chains. Chains run from 0 to 79, so the dot isn't a decimal point here. That catches people out: 12.5 and 12.05 both mean 12 miles 5 chains. You can also write 12m 34ch, or 12 miles 34 chains.

Want the distance between two mileposts? Put a second mileage in. It doesn't matter which way round you type them. Or type kilometres in the last box to get miles and chains, to the nearest chain.

The cream and maroon wooden signal box at Blea Moor behind a dry stone wall, a moor rising behind it
Blea Moor signal box, on the Settle to Carlisle line. Photo: John H Darch, CC BY-SA 2.0

How it is worked out

The units are set in law, so there's no guesswork. The Weights and Measures Act 1985 defines them like this: "Mile = 1760 yards. Furlong = 220 yards. Chain = 22 yards. YARD = 0.9144 metre."

So a mile is 80 chains, a furlong is 10 chains, and a chain is 20.1168 metres exactly. Easy to check by hand. The tool counts everything in chains first, then multiplies out to yards and metres, so there is only ever one rounding, at the very end, when it shows you the answer. 12.34 is 994 chains, which is 21,868 yards or about 19.996 km.

Going back, kilometres are divided by 20.1168 metres to get chains, rounded to the nearest whole chain, and every 80 chains makes a mile. The answer also shows the chains before rounding.

Source: Weights and Measures Act 1985, Schedule 1, Part VI, read 30 October 2026.

Written by Craig Fearn, Trackside Prints. Last updated .

Questions, answered

How many chains are in a mile?
Eighty. A chain is 22 yards and a mile is 1,760 yards.
How long is a chain in metres?
Exactly 20.1168 metres: 22 yards of 0.9144 metres each.
Does 12.5 mean twelve and a half miles?
Not in miles and chains. It means 12 miles 5 chains. Twelve and a half miles would be 12.40.