How to Measure Length in Millimeters

By Society & Culture & Entertainment Last updated Friday, February/14/2025

1). Place the zero mark of the ruler at the left end of an object.
2). Align the ruler with the object.
3). Read the last centimeter number on the ruler at the other end of the object being measured. For example, we'll say it's 4 centimeters.
4). Count how many fraction marks the object you are measuring extends beyond the last whole number. For example, the number of small dashes is 7.
5). Multiply centimeters by 10 and add the number of fraction marks to get the length in millimeters. In the example, the length is 4 times 10 plus 7 or 47 millimeters.
6). Multiply the length in inches if a ruler has only inch units by 25.4 to convert the value to millimeters. For example, 3.5 inches are converted to 3.5 times 25.4 for 88.9 millimeters.