It is traditionally defined as the area of one chain by one furlong (66 by 660 feet), which is exactly equal to 10 square chains, 1⁄640 of a square mile, or 43,560 square feet
If it's one by ten chains, a standard acre isn't even a square shape. Lunacy.
edit. What is a chain...
The chain is a unit of length equal to 66 feet. It is subdivided into 100 links or 4 rods. There are 10 chains in a furlong, and 80 chains in one statute mile.
How about a rod?
The rod or perch or pole is a surveyor’s tool and unit of length exactly equal to 5 ¹⁄₂ yards, 16¹⁄₂ feet, ¹⁄₃₂₀ of a statute mile or one-fourth of a surveyor's chain.
It's like a horrible recursive nightmare of measurements, all related to each other only by arbitrary factors of a third unit...
Oh god, the real definition of an acre...
If it's one by ten chains, a standard acre isn't even a square shape. Lunacy.
edit. What is a chain...
How about a rod?
It's like a horrible recursive nightmare of measurements, all related to each other only by arbitrary factors of a third unit...