Percentage Calculator
Runs entirely in your browser
Calculate a percentage of a number, find what percent one number is of another, or work out a percentage increase or decrease. Everything is calculated directly in your browser.
How to use Percentage Calculator
- Choose the type of percentage calculation you need — "% of a number", "X is what % of Y" or "% increase/decrease".
- Enter the values for that calculation.
- Your result and a plain-language summary update instantly.
Features
- Calculate a percentage of any number.
- Find what percent one number is of another.
- Work out percentage increase or decrease between two values.
- Plain-language summary of every result.
- 100% client-side — your figures are never sent to a server.
Frequently Asked Questions
How do I calculate a percentage of a number?
Choose "% of a number", enter the percentage and the number. The result is the percentage multiplied by the number, divided by 100 — for example, 20% of 500 is 100.
How do I find what percent one number is of another?
Choose "X is what % of Y", enter the two values. The calculator divides the first value by the second and multiplies by 100 — for example, 25 is 20% of 125.
How is percentage increase or decrease calculated?
Choose "% increase/decrease", enter the original ("From") and new ("To") values. The calculator works out ((To − From) / From) × 100 — a positive result is an increase, a negative result is a decrease.
Why do I get an error when the base value is zero?
Percentage calculations that divide by a value — "X is what % of Y" and percentage change — are undefined when that value is zero, since dividing by zero has no meaningful percentage result.
Is my data sent to a server?
No. All calculations happen directly in your browser. The numbers you enter are never uploaded, saved or sent anywhere.