However, Here We Are Talking About Square Miles Which Measures The Area Of Land Rather Than Just Distance. Square miles to acres conversions how many. Convert 100 acres to other units. 26 rows what is 100 acres in square miles? An Acre Is A Unit Of Area Equal To 1/640 Th Of A Square Mile. The other way round this means. What is an acre (ac)? How many miles is 2,000 acres?