Percentage Calculator
Percentage of a number, one number as a percentage of another, and percentage change.
How this calculator works
Three of the most common percentage questions in one place: what a percentage of a value is, what share one value is of another, and how much something rose or fell in percentage terms.
Percentages turn up everywhere — discounts, tax rates, tips, exam scores, pay rises and survey results — yet they are easy to get wrong in your head. The Percentage Calculator bundles the three most common questions into one tool: what a given percentage of a number is, what share one number is of another, and how much something increased or decreased in percentage terms.
The percentage-change calculation is the one people most often muddle, because the direction of the change matters. A rise from 80 to 100 is a 25% increase, but a fall from 100 to 80 is only a 20% decrease — the base you measure from is different each way. The calculator handles this for you so you do not have to remember which number goes on the bottom.
Use it for quick shopping maths (is 15% off a better deal than a fixed discount?), for working out a tip, for interpreting statistics, or for checking a pay review. Each mode is independent, so you can answer one question without filling in the others.
Everything runs in your browser as you type — nothing is stored or sent to a server. Results are estimates for general guidance and should not replace advice from a qualified professional.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 200 is (200 × 15) ÷ 100 = 30.
How is percentage change calculated?
Subtract the original value from the new value, divide the result by the original value, then multiply by 100. A positive result is an increase; a negative result is a decrease.
Why do percentage increase and decrease look different for the same gap?
Because each is measured from a different base. Going from 80 to 100 is a 25% increase (measured from 80), while going from 100 to 80 is a 20% decrease (measured from 100).
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