Since there are 25.4 millimeters in an inch, 10 millimeters is equal to 0.3937 inches, or a little over one-third of an inch. Another common equivalent of an inch in the metric system is 2.54 centimeters.
Since one millimeter is 0.1 centimeters, 10 millimeters is equal to 1 centimeter. Figuring out what 1 centimeter is in terms of inches requires simply dividing one by 2.54. Converting within the metric system is typically easy and is often accomplished by moving a decimal point. For instance, 10 millimeters is equal to 0.1 decimeters and 0.01 meters. Converting between the metric system and the system used in the United States is more difficult and frequently requires mixed numbers.