Place the ruler along the side of an object you want to measure, such as a piece of wrapping paper.
Align the left end of the ruler with one end of the object.
Read from left to right on the ruler until you get to the other end of the object you are measuring. A ruler is divided into inches, which are marked with lines that have a number next to them. Each inch is divided in two with a smaller mark to indicate half-inches, and these half-inches are further divided in two to give you quarter-inches. For precise measurement, your ruler may be divided even more, with markings for 1/16 of an inch and 1/32 of an inch. If you are using a metric ruler, it will be divided by units of 10. A meter is made up of 100 centimeters and 1,000 millimeters. One inch is equivalent to 2.54 centimeters.
Match the end of the object with the nearest inch mark on the ruler, and then see if the object lines up on a half-inch mark, quarter-inch mark or other fraction. You will then see that a piece of paper is 4 1/4 inches long, or that a shelf is 10 1/16 inches wide.