How do you go from mm squared to feet squared? - Answers

To change millimeters squared to inches squared: We will let ~ stand for "approximately equal to". First know that 1 mm ~ 0.0393701 inches. This actually comes from 1 in = 25.4 mm. Therefore your conversion factor could be (1 mm)2 ~ (0.0393701 in)2 or (1 mm)2 ~ 0.00155 in2 But a much easier one is: 1 in2 = 645.16 mm2 This one is exactly equal, so let's use it. Example: Convert 322.58 mm2 to square inches. Answer: Multiply your known number by the factor to change it to the new units: (322.58 mm2) (1 in2/645.16 mm2) = 0.5 in2, or half a square inch.