What is 4 inches to millimeters? The answer is that 4 inches equals 101.6 millimeters.
How to convert 4 inches to mm? We know that one inch is equal to 25.4 millimeters, so to convert 4 inches to millimeters, we must multiply the amount of centimeters by 25.4, which means that 4 inches is equal to 4 inches × 25.4 = 101.6 mm.
See also: How to convert 4 mm to inches.