How to use the surveyor's chain, rod and link converter
- Choose Length or Area.
- Enter the value and pick its unit, such as chains or acres.
- Read the same quantity in every unit in the table, from links to kilometers, or from square links to hectares.
- Use the US survey foot for old deeds in the United States, and the international foot for modern drawings.
Formula
1 chain = 66 US survey feet = 4 rods = 100 links
1 rod (pole, perch) = 16.5 feet; 1 link = 0.66 feet; 80 chains = 1 mile; 10 chains = 1 furlong
1 US survey foot = 1200/3937 meter; 1 international foot = 0.3048 meter
1 acre = 10 square chains = 43,560 square US survey feet
The US survey foot is exact by definition and is about two parts per million longer than the international foot, so a mile differs by about 0.01 foot.
12.5 chains, one mile and 3.5 acres
12.5 chains is 50 rods, 1,250 links, 1.25 furlongs, 0.15625 mile, 825 US survey feet (825.00165 international feet) and 251.4605 meters. One survey mile is 80 chains, 320 rods, 8,000 links and 1,609.3472 meters.
3.5 acres is 35 square chains, 560 square rods, 152,460 square US survey feet, 14,164.054 square meters and 1.4164054 hectares.
Where these units come from
Gunter's chain, 66 feet long, was a convenient length for measuring land: ten square chains make an acre. Surveyors in the English-speaking world used chains and links for centuries, and many deeds, plats and parcel descriptions still use them. A rod, also called a pole or perch, is a quarter of a chain.
Other tools for old measurements include the unit converter and the excavation volume calculator. Curves in surveys are in the horizontal curve calculator, and elevations in the differential leveling calculator.
US survey foot and international foot
The two feet differ by a tiny amount, which matters only over long distances or in large coordinate systems. For a deed that states distances in feet, use the survey foot unless the deed says otherwise. The unit in an old description can also be a local one, so check what the document means before using any conversion.
Assumptions and limits
- Chains, rods and links are those of Gunter's chain, 66 US survey feet long.
- Miles, furlongs and square miles are the survey versions based on the US survey foot.
- Inches and yards are international units, with 1 inch = 0.0254 meter and 1 yard = 0.9144 meter.
- The page converts numbers. It does not interpret a deed or a boundary, which is a job for a licensed surveyor.
Frequently asked questions
How many feet are in a chain?
A surveyor's chain is 66 feet, which is 4 rods or 100 links. Eighty chains make a mile.
How many square chains are in an acre?
Exactly 10. A square chain is 4,356 square feet and an acre is 43,560 square feet.
How long is a link?
One link is 0.66 foot, or 7.92 inches, because a chain has 100 links.
What is the difference between a rod, a pole and a perch?
None. All three names mean 16.5 feet, a quarter of a chain.