How to Read a Ruler

Most people learn to read a ruler when they are very young, but the lesson might not stay with them their entire life. Depending on a person’s hobbies and career, there might not be many options in which he would need to read a ruler. However, it is an important skill, so understanding how to do it will eventually come in handy. An incorrect ruler reading can lead to poor results when working on a project. Understanding how to read a ruler is also an important skill a parent can pass on to a child.

It is possible to get by only focusing on the inch and half-inch marks on a ruler. The smaller lines provide more accurate measurements, which are sometimes not necessary. Sometimes approximate measurements are good enough, but some projects require very specific calculations. The key is understanding when specific measurements are needed and when basic estimates are good enough. The average ruler has inch and half-inc marks, as well as sixteenth, eighth, and quarter inch marks.

Rulers, Yard Sticks, and Tape Measures

Rulers are usually 12 inches long. Yard sticks are obviously a yard in length and tape measures vary in length. Most of them are read the same, but when referring to a ruler, the standard size is 12 inches. There are numbered markings at each full inch, and lines of varying sizes marking the fractions of an inch. The half inch mark is the longest and the quarter and eighth inches decrease in size. When making precise measurements, you might need to count off the lines. The more experience you have the easier it is to counter your measurements with just a glance.


If you really want to understand how to read a ruler it is important to understand fractions. Exact measures usually include fractions, so ruler users need to know how to convert fractions to numbers that make sense. Most directions will include measurements in the lowest form. You need to be able to translate the standard measurements to those on your ruler. For instance, if you have a standard ruler with sixteenth of an inch lines and you are told to cut a piece of wood 5 and ¼ inches in size, you will need to translate this fraction into the sixteenth of an inch measurement. In this case, you will want to measure to the five inch mark and then count off four of the sixteen lines on the ruler.

Adding Ruler Measurements

Adding measurements is another important part of reading a ruler. If you are trying to build something you might need to combine measurements to accurately build your final piece. In most cases, adding measured pieces involves adding fractions. If you cut a piece of wood that is 2 3/16 of an inch and 5 and 4/16 of an inch, you end up with a final measurement of 7 and 7/16 of an inch. However, if you are trying to add fractions with different denominators, you need to convert the fraction. If the original numbers are 2 and 3/16 and 5 and ¼, you get the same outcome, but you need to translate ¼ into 4/16 before proceeding. With practice, measuring with a ruler and converting measurements get easier. If you are concerned about your ruler reading skills, take time to practice and it will become much easier.