Fractions

Percents and decimals

Knowing how to convert percents and decimals will help you calculate things like sales tax and discounts. To learn how, check out our Percents in Real Life lesson.

Converting a percent into a decimal

Converting a percent into a decimal is surprisingly easy. It only takes a few simple steps.

Click through the slideshow to learn how to convert a percent into a decimal.

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  We're going to convert 17% into a decimal.

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  First, we'll take the percent sign...

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  First, we'll take the percent sign...and turn it into a decimal point.

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  Next, we'll move the decimal point two spaces to the left.

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  Now we'll move the decimal point two spaces to the left.

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  We've converted our percent to a decimal. 17% is equal to 0.17.

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  Let's look at another example. This time we'll turn 78% into a decimal.

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  First, we'll replace the percent sign with a decimal point.

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  Then we'll move the decimal point two spaces to the left.

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  Then we'll move the decimal point two spaces to the left.

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  78% is equal to 0.78.

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Why does this work? 

Converting percents into decimals is so easy that you may feel like you've missed something. But don't worry—it really is that simple! Here's why the method we showed you works.

When we turn a percent into a decimal, we're actually doing two steps. First, we convert our percent into a fraction. Since all percents are out of 100, we just put the percent over 100, like this:

78% = 78/100

In the second step, we convert 78/100 into a decimal. You already know this means we'll divide the numerator by the denominator, like this:

78 ÷ 100 = 0.78

So why didn't we show you these steps in the slideshow? Because you can get the answer without them. You know that all percents are out of 100, so you can skip making the percent into a fraction. You have to divide the percent by 100 to get a decimal, but there's a quick way to do that. Just move the decimal point two spaces to the left! This way, you can get the same answer with just one easy step.

 Now you try it! Convert these percents into decimals.

Converting a decimal into a percent

Now we'll reverse what you just learned. Let's convert a decimal into a percent.

Click through the slideshow to see how to convert a decimal into a percent.

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  We're going to convert 0.45 into a percent.

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  We'll reverse what we did in the last section. This time, we'll move the decimal point two places to the right.

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  We'll reverse what we did in the last section. This time, we'll move the decimal point two places to the right.

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  Now we'll replace the decimal point with a percent sign.

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  We've finished converting our decimal into a percent. 0.45 is equal to 45%.

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  Let's try another example. This time our decimal has three numbers to the right of the decimal point.

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  But we're still going to move the decimal point two spaces to the right.

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  But we're still going to move the decimal point two spaces to the right.

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  We still have a number to the right of the decimal point. The number isn't a 0, so we can't drop it.

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  Instead, we'll keep the decimal point and add a percent sign at the end of the number.

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  So 0.635 is equal to 63.5%.

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Now it's your turn. Calculate these decimals as percents.