A ruler measurement chart is read exactly the way a regular ruler is read. When reading a ruler measurement chart, the user must identify if it is a fractional/English ruler or a decimal/metric ruler. Rulers in the United States are English rulers with the primary unit of measurement being inches.
English rulers are divided into inches and fractions of inches. A standard ruler is 1 foot long and is divided into 12 inches. Each inch mark is numbered and is further subdivided into fractions of inches. The number of subdivisions depends on the kind of ruler. Depending on the ruler, an inch can be subdivided into 8 parts or 16 parts.
The next smallest line on a ruler in comparison to inch marks is 1/2 inch. The next smallest lines relative to the previous smallest lines are 1/4, 1/8 and 1/16 inch respectively. Therefore, when measuring using a ruler measurement chart, the whole inch is marked followed by the fraction of the inch. Distances such as 2 1/2, 4 5/8 and 7 5/16 inches can be marked using a English ruler measurement chart.
The units of measurement in metric rulers are centimeters and millimeters. The longer lines are centimeters, and each centimeter is divided into 10 parts with each representing a millimeter. If eight marks are counted after a centimeter, the measurement is 1.8 centimeters.