Fraction to Percent Converter
Convert a fraction or ratio to a decimal and a percentage, or change a percent back into a simplified fraction.
This converter runs entirely in your browser. Nothing you type is uploaded or stored.
How to use this tool
Pick a mode at the top of the box. In Fraction to percent mode, type the numerator (the top number) and the denominator (the bottom number), choose how many decimal places you want, then press Convert to percent. The tool shows the decimal value and the matching percentage. Switch to Percent to fraction mode to enter any percentage and get it back as a simplified fraction. Use the copy button to grab the answer for a worksheet, spreadsheet, or report.
The formula: how fraction to percent conversion works
Example: 3 / 4 = 0.75, and 0.75 x 100 = 75%
Reverse (percent to fraction): fraction = percent / 100, then divide top and bottom by their greatest common divisor (GCD).
A fraction is just a division waiting to happen. Dividing the numerator by the denominator gives a decimal, and multiplying that decimal by 100 turns it into a percentage. The word "percent" literally means "per hundred", so a percentage is the value the fraction would have if the denominator were 100. The same logic powers a ratio to percentage conversion: a ratio like 1:4 is the fraction 1/5 of the whole once you add the parts, and that becomes 20%.
Going the other way, every percentage is a fraction over 100. To simplify it, the tool finds the greatest common divisor of the top and bottom numbers and divides both by it. Decimal percentages (like 12.5%) are first scaled up by powers of ten so the fraction stays whole before it is reduced, which is the fraction decimal scaling step that keeps the answer exact.
A real example
Say a student answered 18 questions correctly out of 24 on a quiz. Enter 18 as the numerator and 24 as the denominator. The decimal is 18 / 24 = 0.75, and multiplying by 100 gives 75%. Now switch to percent mode and enter 75: the tool returns 3/4, because 75/100 reduced by its GCD of 25 becomes 3/4. Both directions describe the very same value, just in different forms.
Common questions
How do I convert a fraction to a percent by hand?
Divide the numerator by the denominator to get a decimal, then multiply that decimal by 100 and add a percent sign. For example, 3/4 = 0.75, and 0.75 x 100 = 75%.
Can this tool turn a ratio into a percentage?
Yes. Write the ratio as a fraction first. A ratio of 1:4 means 1 part out of 5 total parts, so enter 1 over 5 to get 20%. For a part-to-whole ratio you can enter the numbers directly.
Why does the percentage have repeating decimals?
Some fractions, like 1/3, do not divide evenly, so the percentage is 33.33... You can choose more or fewer decimal places to round the answer to the precision you need.
How does the percent to fraction conversion simplify the answer?
The percentage is written as a fraction over 100, then both numbers are divided by their greatest common divisor. Decimal percentages are scaled by powers of ten first so the fraction stays whole before it is reduced.
Can the denominator be zero?
No. Dividing by zero is undefined in mathematics, so the tool will ask you to enter a denominator that is not zero.