Read the length of an object by counting the whole-inch markers in between the ruler's zero-inch line and the object's end and then measuring the fraction of the last inch by counting the remaining small increments. English rulers are typically divided into fourths, eighths, 16ths and occasionally 32nds.
Inch lines on a ruler are typically the longest black lines on the ruler, and they have integer numbers next to these lines. To determine whether a ruler's increments are divided into fourths, eighths, 16ths or 32nds, count the number of increments between the zero-inch line and the one-inch line.
To measure the length of an object, line up the edge of an object with the zero-inch line. Count the number of integer lines between the zero-inch line and the end of the object. If the end of the object lies between two inch lines, count the number of small increments, starting at the lower of the two inch lines, until reaching the end of the object. The number of increments counted represents a fraction of an inch in terms of how they are divided.