Fraction to Percentage Calculator

How it works

A fraction represents a division. To convert it to a percentage, divide the top number (numerator) by the bottom number (denominator) to get a decimal, then multiply by 100 to express it as a percentage.

The formula

Why this works: A percentage is simply a fraction with a denominator of 100. Dividing the numerator by the denominator converts the fraction to a decimal, which represents its value relative to 1. Multiplying by 100 then scales it to the per-hundred format that a percentage requires.

Worked examples

When to use this

Any time you have a part-out-of-whole figure and need to express it as a percentage, this calculator does the conversion in one step.

• Exam and coursework marks. A GCSE English paper marked 38 out of 50 converts to 76%. Knowing the percentage makes it straightforward to check against published grade boundary tables from AQA, OCR, or Edexcel.
• School attendance records. A pupil who attended 187 out of 190 school days in a term has 187/190 = 98.4% attendance, comfortably above the 90% threshold that schools flag for intervention.
• Budget tracking. A department has spent £14,200 of a £20,000 quarterly budget. 14,200/20,000 = 71%, so 29% of the budget remains with several weeks still to run.
• Sports and performance statistics. A Premier League goalkeeper saves 11 of 14 shots on target. 11/14 = 78.6% save rate, which sits among the stronger performers in the division that season.
• Nutritional labels. A 250g serving contains 85g of carbohydrate. 85/250 = 34% of the serving is carbohydrate, useful when tracking macros against a daily target.

Understanding the result

When the numerator is smaller than the denominator, the percentage will always be below 100%. When they are equal, the result is exactly 100%. If the numerator exceeds the denominator, for example a machine that produced 105 units against a target of 100, the percentage will be above 100%, which is perfectly valid.

Some fractions produce recurring decimals. One third (1/3) gives 33.333..., which is typically rounded to 33.33% or 33.3% depending on the context. Two thirds (2/3) gives 66.67%. This rounding is fine for most practical purposes, but if you need exact values in further calculations, keep the fraction form rather than converting it.

If your result looks unexpectedly high or low, check that the numerator and denominator are not swapped. When the fraction represents a part of a whole, the part goes in the numerator and the total goes in the denominator.

Related concepts

• ➡ convert any percentage into its simplest fraction form in lowest terms
• ➡ convert a decimal score into a percentage in one step
• ➡ look up which grade band your percentage result falls into

How to do this in Excel

In Microsoft Excel or Google Sheets, put the numerator in cell A1 and the denominator in cell B1, then enter this formula in C1:

This divides A1 by B1 and multiplies by 100, returning the percentage as a plain number. If you prefer the % symbol, omit the *100 and instead format the cell as Percentage via Format Cells > Number > Percentage. Excel then handles the scaling automatically.

How to do this without a calculator

For common fractions, use known percentage equivalents: a half is 50%, a quarter is 25%, three quarters is 75%, a fifth is 20%, two fifths is 40%, three fifths is 60%, four fifths is 80%, an eighth is 12.5%, and a tenth is 10%. These are worth memorising because they appear constantly in everyday life.

For other fractions, try converting the denominator to 100 or 1,000 first. For 7/20, multiply both top and bottom by 5 to get 35/100, which is immediately 35%. For 3/8, multiply by 125 to get 375/1,000 = 37.5%.

If the fraction cannot be converted cleanly, divide top by bottom using long division. For 5/6: 5.0000 divided by 6 gives 0.8333, so the percentage is 83.33%. Round to two decimal places for most purposes.

Common mistakes

Related calculators