Decimal To Percent Calculator

What this calculator does

So, you have a decimal like 0.25 and you want it as a percentage, 25%. This tool multiplies the decimal by 100 and shows the percent to two decimal places.

There is one box, for the decimal. Type the number and it returns the percentage.

How to use it

1. Type your decimal number.
2. Press Calculate.

Any decimal works, whether it is a proportion below 1 like 0.4 or a value above 1 like 1.5.

Multiplying by 100 slides the point two places right

A percentage is a number of hundredths, so to turn a decimal into one you multiply by 100. And multiplying by 100 has the same tidy shortcut as its opposite, only mirrored: slide the decimal point two places to the right. 0.25 becomes 25, 0.4 becomes 40, and 1.5 becomes 150. The digits stay put; only the point moves, in the other direction from dividing.

The method it uses

Multiply the decimal by 100 and add the percent sign. That is all of it. 0.25 times 100 is 25, so 0.25 is 25%. 0.07 times 100 is 7, so 0.07 is 7%. The tool rounds the result to two decimal places, so a longer decimal like 0.333 comes out as 33.30%.

A worked example, step by step

Take 0.625.

• Multiply by 100: 0.625 × 100.
• Slide the point two places right: 0.625 becomes 62.5.
• So 0.625 is 62.50%.

The same move turns 0.4 into 40% and 1.2 into 120%.

Why a raw decimal is worth converting

A decimal like 0.375 is exact, but it does not land as quickly with most people as 37.5% does. Percentages put a value on a familiar scale, out of 100, that we are trained to read at a glance. A test score of 0.82 means less to the eye than 82%. A growth of 0.03 reads faster as 3%. The decimal is the value; the percentage is the way to say it so it registers.

The reverse trip: percent to decimal

This tool goes from a decimal to a percent. To go the other way, you divide the percent by 100, sliding the point two places left, which the percent to decimal calculator does. Fraction, decimal, and percent are three ways of writing the same value, so each conversion just moves between two of them.

Questions people ask

Why multiply by 100?

Because percent means by the hundred. Multiplying a decimal by 100 expresses it as a count of hundredths, which is the percentage.

Is there a shortcut?

Yes. Multiplying by 100 is the same as sliding the decimal point two places to the right, so 0.45 becomes 45%.

What if the decimal is more than 1?

Then the percentage is more than 100. 1.5 becomes 150%, which is perfectly valid and just means one and a half times the whole.

How many decimal places does it show?

Two. A longer decimal such as 0.333 is rounded, so it appears as 33.30%.

How do I turn a percent back into a decimal?

Use the percent to decimal calculator, which divides by 100. It is the inverse of this tool.

References

On expressing a decimal per hundred. Multiplying a decimal by 100 and appending the sign gives a percentage, a notation that grew from the Italian per cento, by the hundred.

1. Eric W. Weisstein, "Percent," from MathWorld, a Wolfram resource, which notes that a ratio is converted to a percentage by multiplying by 100 and appending the % sign.
2. "Percentage," Wikipedia, on percent from the Latin per centum and the % sign's origin in the Italian per cento.