On a miter saw, when you're cutting a 90 degree cut, the miter saw reads zero. On a protractor, it reads 90. So it's an unending source of confusion for people. RON HAZELTON: So Mark, show me how it works.
A ruler is used to measure units of length, inches, feet and yards. Standard rulers have inches on one side and centimeters on the other. A typical ruler measures up to 12 inches, and is equivalent to 30.48 centimeters. This is also equivalent to 1 foot. Each inch on a ruler has markings in between that are a fraction of an inch.
Inches are generally marked with a number and a longer line. Half-inches, 1/4 inches, 1/8 inches and 1/16 inches are marked with increasingly shorter lines. One-half inch is midway between the left end of the ruler and the 1-inch mark. On a ruler dividing the inches into eighths, 5/8 inch is the next line. On a ruler dividing inches into 16ths, it is two lines from the half-inch mark. Learn more about Measurements