How to Change a Ratio Into a Decimal

By David Boyles

A ratio is a quantity that expresses the proportional amount of one quantity in relation to another. For example, if there are 2 boys and 3 girls in a class, we would write the ratio of boys to girls as 2:3. Sometimes, we will need to write ratios as a decimal. The steps below will show you how to convert ratios into decimals.

Write the ratio as a fraction. As stated earlier, ratios are typically written with a colon. In our example, the ratio of boys to girls is 2:3. The ratio can be converted to a fraction by replacing the colon with a fraction bar. For example, 2:3 can be written as 2/3.

Divide the numerator (top number) by the denominator (bottom number) in your fraction. In our example, if you divide 2/3, you get .666666.

If necessary, round the decimal. If your decimal goes on for several places, as our example does, you will need to round it. Sometimes, you may be asked to round to a certain number of places. If not, round to two decimal places. So, we would round our number to .67.

Express your answer as a ratio. So, the ratio of boys to girls in the class is .67.

About the Author

David Boyles is a graduate student, teacher and professional writer. He has been teaching writing since 2005, while his own work has been featured in various publications and websites, including "Vegas Seven," "ArtsVegas," "AZ on the Scene Magazine" and the "Las Vegas Review of Books." Boyles holds a master's degree in English literature.