What is 20 inches to millimeters? The answer is that 20 inches equals 508 millimeters.
How to convert 20 inches to mm? We know that one inch is equal to 25.4 millimeters, so to convert 20 inches to millimeters, we must multiply the amount of centimeters by 25.4, which means that 20 inches is equal to 20 inches × 25.4 = 508 mm.
See also: How to convert 20 mm to inches.