Inches and millimeters are two commonly used units for measuring length. Because inches are imperial measurements and millimeters are metric, there is no whole-number conversion. Millimeters are converted to inches by using the conversion rate, or they can be compared on opposite sides of a ruler.Continue Reading
The exact conversion rate from millimeters to inches states there are 25.4 millimeters in 1 inch, or that 0.039370 inches equals 1 millimeter. You can approximate 25 millimeters for each inch when making quick estimates.
To cancel millimeters and turn them into inches, multiply any number of millimeters by 0.039370 inch/millimeter. Therefore, 250 millimeters x 0.039370 inch / 1 millimeter = 9.8425 inches. Alternatively, if you are estimating and know that 25 millimeters is approximately 1 inch, you can multiply by the fraction 1 inch/25 millimeters. Therefore, 250 millimeters x 1 inch / 25 millimeters = 10 inches. Estimate by first converting the millimeters to centimeters. There are 10 millimeters in every 1 centimeter and approximately 2.5 centimeters in every inch.
There is 0.04 or 1/25 inch in each millimeter. Your answer will produce a number much smaller for inches than the measurement in millimeters. You can also check a ruler to see how many millimeters are equal to an inch.