Free tool
Survey unit converter
Convert lengths, areas and volumes, including the old units that still turn up on titles and plans: chains, links, rods, perches and acres.
Method and limits
- All factors come from the international foot, defined as exactly 0.3048 m: a Gunter's chain is 66 ft (20.1168 m), a link is 0.66 ft (0.201168 m), a rod, pole or perch is 16.5 ft (5.0292 m), an acre is 43,560 square feet (4,046.8564224 m2), a perch (square rod) is 272.25 square feet and a rood is 10,890 square feet.
- The US survey foot is 1200/3937 m, about 2 parts per million longer than the international foot. It was retired in the US at the end of 2022 but still appears in older data. Make sure you know which foot a document uses.
- Historic title measurements are in old units and can be in link, chain and perch. This tool converts the numbers; it does not tell you what a title means.
- Factors were checked against exact fractions. Results show up to 12 significant figures.
- This tool is a convenience, not a survey deliverable. Check results against your own work, and use certified methods for anything you sign off. Provided as is, in line with the terms. Nothing you enter is sent anywhere.