Everyday maths · Free · No signup
One calculator. Every percentage.
Find a percentage, compare two values, or work out a price after a discount or increase. Use pounds, dollars or any unit—just keep the units consistent.
Results display up to 8 decimal places. Calculations use standard browser floating-point arithmetic.
How to use the percentage calculator
- Choose your calculation from the menu.
- Enter both values. For percentage change, enter the original value first and the new value second.
- Select Calculate to see the answer and the formula.
Percentage formulas with examples
Percentage of a number: divide the percentage by 100, then multiply by the number. For example, 15% of 200 is 30.
Percentage change: (new − original) ÷ original × 100. A rise from 80 to 100 is a 25% increase. This tool uses a positive original value so the direction stays clear.
Percentage difference: the absolute difference divided by the average of two nonnegative values, multiplied by 100. Comparing 80 and 100 gives approximately 22.22%. Neither value is treated as the starting point.
Discount: original price × (1 − discount ÷ 100). A £120 or $120 item with 25% off costs 90 in the same currency.
Frequently asked questions
What is the difference between percentage change and percentage points?
A change from 20% to 25% is 5 percentage points, but the relative increase is 25%. Enter 20 and 25 in percentage change mode to calculate the relative increase.
Can I calculate a percentage from zero?
A percentage change from zero and a ratio with a zero denominator are undefined. The calculator shows an explanation instead of an infinite or misleading result.
Can I use decimals and negative values?
Decimals work in all modes. Basic percentage calculations allow negative values. Change mode requires a positive starting value and a nonnegative final value; price calculations require nonnegative values.
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