To use a ruler, place it alongside or on top of the object or line that is to be measured and count the number of marks from edge to edge of the object. For those who are working with a metric ruler, the longer lines are denoted by a numerical value and represent centimeters, with ten smaller lines placed in between each centimeter, denoting a millimeter. For those who are working with English rulers, each of the longer lines indicate an inch, with eight smaller lines separating each inch to represent the length of 1/8th of an inch.
Most professionals recommend lining up the object or line that is to be measured with one end at zero, which is found at the left end. Some rulers are quite stiff as they are made from wood or plastic, which makes it difficult to wrap them around objects if they are to be measured; however, there are also some that are made from more flexible materials. There are also printable rulers that are available online.
Regardless of whether an individual has measured in centimeters or inches, both of these measurements are interchangeable and can be easily converted. There are 2.54 centimeters in each inch.