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.
Measuring an Object Using a Ruler. 1  1. Measure with a ruler or tape measure. 2  2. Place the zero end of your rule at the end of your object. 3  3. Move to the opposite side of the object you are measuring.  4. Use a metric or decimal rule with a metric 1  ruler. 5. Use a tape measure to measure between objects, for instance, walls.