Square Chain (sq ch)

US & ImperialTraditional unit (still used in some regions)

484 square yards (404.69 m²), one tenth of an acre. A surveying unit.

1 square chain = 404.6856422 square meters (approximately).

About the square chain

Surveyors rather than farmers gave this unit its shape. In 1620 the English clergyman and mathematician Edmund Gunter devised a measuring chain of 100 links that was 66 feet long, and by 1675 it was in wide use. A square chain, 66 feet by 66 feet, covers 4,356 square feet, or 484 square yards. The convenient result is that ten of them make exactly one acre, so a plot measured in chains could be turned into acres by moving a decimal point.

That arithmetic was the reason the US adopted the chain. A report by Thomas Jefferson in 1784 led to the Land Ordinance of 1785, which required the chain for surveying the public lands, and many American property lines still trace back to chain measurements. In metric terms a square chain is about 404.69 square meters. The linear chain remains in niche use, for example in railway milepost distances in Britain, in wildfire spread rates in the United States, and as the length of a cricket pitch.

Sources: Wikipedia: Chain (unit); Wikipedia: Acre; Wikipedia: Rod (unit)

Square Chain conversion chart

1 square chain expressed in every other area unit:

More US & Imperial units

• square inch (area)
• square foot (area)
• square yard (area)
• acre (area)
• square mile (area)
• square rod (area)
• inch (length)
• foot (length)
• yard (length)
• mile (length)
• thou (length)
• league (length)
• furlong (length)
• chain (length)
• rod (length)
• link (length)

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