How to Read the Different Measurements on the Ruler

Rulers can be either metric of American standard.

Rulers are useful for students in math and geometry classes, as well as for individuals who need to measure for tasks such as making crafts, home improvements and sewing. Reading a ruler correctly is essential for using it efficiently. Most rulers have either metric measurements, standard American measurements or both. You can learn to read a ruler by understanding a few basic principles.

Instructions

Metric Measurements

1. Notice the larger line markers. These indicate centimeters and usually are numbered in order from left to right.

2. Take a look at the smaller dividing marks between the larger marks that indicate centimeters. These are millimeter marks. There are 10 millimeters in every centimeter.

3. Read a measurement in terms of centimeters or millimeters. For instance, if you are measuring an object that reaches to the fifth millimeter mark beyond the second centimeter mark, you could read it as "2.5 centimeters" or "25 millimeters." Multiply centimeters by 10 to get millimeters. Divide millimeters by 10 to get centimeters.

Standard American Measurements

1. Observe the larger lines that are numbered. These are inches and increase from left to right.

2. Notice the smaller lines dividing the inches. If there are eight marks between the inch marks, then each of these marks is an eighth of an inch. If there are 16 small marks between the inch marks, then each of these marks is a 16th of an inch.

3. Observe the lines that are slightly longer than the smallest marks but slightly smaller than the inch marks. These medium-length marks denote fourths (or quarters) of an inch. The medium-length mark in the center between two inch marks shows a half of an inch.

4. Interpret measurements in terms of inches and fractions. For instance, if you measure something that reaches the fifth mark of the eight small marks between the third and fourth inches on a ruler, you would read that measurement as 3 5/8 inches.

References

• Online Conversion: How Do I Read a Ruler?