Link (unit)

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Link (unit)

The link, also called a Gunter’s link, is a historical unit of length used in many English‑speaking countries. It comes from Gunter’s chain, a 66‑foot measuring tool.

Key facts
- Length: 1 link = 0.66 feet = 7.92 inches ≈ 20.12 cm.
- It fits into other old units: 25 links = 1 rod; 100 links = 1 chain; 1,000 links = 1 furlong; 8,000 links = 1 mile.
- Absolute length varies slightly with different foot definitions, but commonly:
- about 201.168 mm (international foot),
- about 201.16765 mm (imperial foot, per 1959 standard),
- about 201.16840 mm (US survey foot).

Origins and history
- The link is based on Gunter’s chain, a 66‑foot measuring device used in surveying.
- Edmund Gunter introduced the chain in 1620 to simplify land measurement and calculations.
- The yard and foot lengths were standardized over time, with the international yard fixed at 0.9144 meters in 1959.
- In the United States, surveying long used the US survey foot; efforts began to retire it around 2022, aligning U.S. units with the international foot.

Usage today
- The link is mostly obsolete in everyday use, but it remains part of historical measurements and surveying history.

See also
- Edmund Gunter

Note: 25 links make a rod, 100 links make a chain, 1,000 links make a furlong, and 8,000 links make a mile.