how big is 1 acre in square feet
Acre The acre is a unit of land area used in the imperial and US customary systems. It is defined as the area of 1 chain by 1 furlong (66 by 660 feet), which is exactly equal to ​1⁄640 of a square mile, 43,560 square feet, approximately 4,047 m2, or about 40% of a hectare.
Katha (unit) 1 decimal in Bihar equals to 435.56 sq feet.[3][4][5]