Chain to Mile Converter

chain to mile – How to convert ch to mi

The chain is one of those units that feels like it belongs in the pages of an old surveying handbook — and in a way, it does. But it also remains part of real-world property descriptions, legal boundaries, and mapping systems, especially in the U.S. and U.K. If you’re reading old land records or working on a rural survey, converting chains to miles helps bring those distances into a more familiar scale.

Here’s how the conversion works and why it’s still relevant today.

What is a chain (ch)?

A chain is a traditional unit of length equal to:

1 chain = 66 feet = 22 yards = 100 links

It was standardized in the 1600s by English mathematician and surveyor Edmund Gunter, whose “Gunter’s chain” became a foundational tool for land surveying. Chains are still referenced in:

• Land deeds and boundary maps

• Rural property measurements

• Railway and pipeline layouts

• Farming and field plotting

Despite its old-school origin, the chain provides easy-to-work-with ratios. For example, 10 chains make a furlong, and 80 chains make a mile — which brings us to our next unit.

What is a mile (mi)?

A mile is an imperial unit of length used widely in the United States and the United Kingdom. It's defined as:

1 mile = 5,280 feet = 1,760 yards = 80 chains

Originally based on Roman measurements and later standardized by the British, the mile is still used today for road distances, speed limits, and land area descriptions. It's a common go-to unit when expressing longer distances that aren’t quite large enough to need kilometers.

How to convert chains to miles

This is one of the most straightforward conversions in historical units:

1 mile = 80 chains

So the formula is:

miles = chains ÷ 80

Example conversion

Let’s convert 240 chains to miles:

miles = 240 ÷ 80
miles = 3

So, 240 chains is equal to 3 miles.

Want to skip the math? Use the Length Converter to instantly convert chains, miles, and other units. For more measurements, check out the full Conversion tools collection.

Did you know?

• The Public Land Survey System (PLSS) used in the United States was built on chain-based measurements — each section of land is one square mile, or 80 chains by 80 chains.

• A furlong, often used in horse racing, is exactly 10 chains, or 1/8 of a mile.

• Many old railroads and highways were measured and documented using chains — and some engineering maps still reference them.

• In early agriculture, fields were often plowed and measured in chain lengths, especially for crop rotation planning.

• The term “chainage” is still used in civil engineering to denote distance along a curve or alignment — though the units are often metric today.

From colonial boundaries to modern blueprints

Back in the 1700s and 1800s, surveyors used metal chains to physically measure property lines across the American frontier. It was slow work, but the simplicity of the chain-mile relationship made it perfect for dividing land into townships, sections, and ranges.

Even today, this measurement system defines legal land descriptions across large parts of the U.S. A surveyor might note a property boundary as extending "17.5 chains north" — and with one quick calculation, that’s just 0.21875 miles.

In civil engineering, older bridges and roadways often have their position markers based on chain measurements. Converting them to miles gives a clear picture of the total span without losing historical context.

Still useful after 400 years

To convert chains to miles:

miles = chains ÷ 80

It’s a simple calculation, but one that still shows up in legal land work, historical research, and long-distance infrastructure planning. Even in today’s digital world, the chain remains a valuable link to our surveying roots.

Use the Length Converter for fast results, or explore other historical and modern measurements with the full set of Conversion tools.