One English acre measures 4,840 square yards.
One Scottish acre measures 6,150 square yards (or 1 English acre, 1 rood and 1 ⁴⁹³⁄₆₂₅ square poles).
One Irish acre measures 7,840 square yards (or 1 English acre, 2 rood, and 10 ²⁷⁄₁₂₁ square poles).
One Welsh acre measures 9,680 square yards (or 2 English acres).
The Devonshire (customary) acre measures 4,000 square yards.
The Lancashire acre measures 7,840 square yards.
The Cheshire/Staffordshire acre measures 10,240 yards (the Cheshire acre is sometimes given as the same as a Welsh acre, however)