How do you convert 250 millimeters to inches?

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.

1. Know the conversion rate

   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.

2. Multiply or estimate

   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.

3. Check your answer

   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.