Land records · Parcel maps · October 6, 2026
What Is a Chain in Land Measurement? 66 Feet
What is a chain in land measurement? A Gunter's chain is 66 feet, or 100 links. It sets the size of acres, sections, and many old deed distances.
What is a chain in land measurement? A chain, specifically a Gunter’s chain, is a unit of length equal to 66 feet. It is divided into 100 links of 7.92 inches each, and 4 rods make a chain. The chain shaped much of American land: an acre is 10 square chains, a mile is 80 chains, and the public land survey laid out sections one mile, or 80 chains, on a side. Old deeds and government survey notes often give distances in chains and links. This page is general land-records background, not legal advice.
Conversions
| Unit | Equals |
|---|---|
| 1 chain | 66 feet, 4 rods, 100 links |
| 1 link | 7.92 inches (0.66 feet) |
| 1 rod (pole, perch) | 16.5 feet, 25 links |
| 80 chains | 1 mile |
| 10 square chains | 1 acre |
| 1 furlong | 10 chains, 660 feet |
Why 66 feet?
Edmund Gunter designed the chain in the 1600s so that it fit existing English measures neatly. A chain was four rods, an acre was a strip one chain wide and ten chains long, and decimal links made area math easy. That convenience kept it in use for centuries, and U.S. federal surveyors used chains well into the 1900s.
Reading chains in a deed
A deed might say “thence north 12 chains 50 links.” Convert by multiplying chains by 66 and links by 0.66: 12 × 66 = 792 feet, plus 50 × 0.66 = 33 feet, for 825 feet. Some writers use decimals: “12.50 chains” is the same 825 feet. Watch for “ch.” and “lks.” abbreviations.
Chains in the public land survey
Government land office survey notes recorded section lines in chains. Quarter corners sit at 40 chains, and sixteenth corners at 20 chains, along a standard section line. Our guide to township and range shows how sections were laid out.
Other old units you may see
Spanish and French colonial areas used different units. Texas and the Southwest have the vara, and Louisiana and parts of the Mississippi valley have the arpent. See also the rod.
Accuracy of old chain measurements
Chains stretched with wear, and crews measured over brush, hills, and creeks. A modern survey may find that an old “40 chain” line is a few feet long or short. Surveyors generally hold original monuments over measured distances when the two disagree.
Quick area math with chains
Because an acre is 10 square chains, chain distances make area estimates easy. A rectangle 5 chains by 8 chains is 40 square chains, or 4 acres. A quarter-quarter section, 20 chains on a side, is 400 square chains, or 40 acres. A full section, 80 chains by 80 chains, is 6,400 square chains, or 640 acres. That simple relationship is one reason chains stayed popular with land offices long after other units were standardized.
Chains on modern documents
Modern surveys and plats in the United States give distances in feet, usually to the hundredth of a foot. When a new survey retraces an old chain-based description, the surveyor typically shows both: the record distance in chains, converted to feet, and the measured distance. A note such as “record 20.00 ch (1320.00’), measured 1321.47’” is common and does not by itself mean anything is wrong. Small differences reflect the limits of old equipment, not a change in where the line is.
Bottom line
A chain is 66 feet, divided into 100 links, with 4 rods per chain and 80 chains per mile. Ten square chains make an acre. When an old deed or survey gives distances in chains and links, multiply chains by 66 and links by 0.66 to get feet. Find county plats and land records via the Platbookmapper map.
What is a chain in land measurement FAQ
How many feet are in a chain?
A Gunter’s chain is 66 feet.
How many links are in a chain?
100 links, each 7.92 inches long.
How many chains are in a mile?
80 chains.
How many square chains are in an acre?
10 square chains make one acre.
What is an engineer’s chain?
A separate 100-foot chain used in some engineering work. Land deeds almost always mean the 66-foot Gunter’s chain.