Units of Measurement

Hectare -
Metric unit of area equal to 10,000 square meters, or 2.471 acres

Acre -
The (English) acre is a unit of area equal to 43560 square feet, or 10 square chains, or 160 square poles or 4840 square yard

 Square mile = A square mile is 640 acres 1 acre = 4840 square yards. 1 square yards = 9 square feet 1 square meter = 1.2 square yard 1 square foot = 144 square inches 12 inches = 1 foot 3 feet = 1 yard 1 chain = 22 yards or 66 feet 10 chains = 1 furlong

Chain -
Unit of length usually understood to be Gunter's chain , but possibly variant by locale. The name comes from the heavy metal chain of 100 links that was used by surveyors to measure property bounds.
Engineer's Chain -
A 100 foot chain containing 100 links of one foot apiece
Gunter's Chain -
Unit of length equal to 66 feet, or 4 poles. This unit was apparently defined as one tenth of a furlong, a common unit of length in the old days. The mile was redefined from 5000 feet to 5280 feet in order to be an even multiple of furlongs. A mile is 80 chains
Hide -
Old English unit of area usually equal to 120 acres.