Percentage Calculator
Percent of a number, percentage change and difference, increases, discounts and reverse percentages.
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How to use
- Pick the calculator that matches your question.
- Type the numbers into the sentence — the answer updates instantly.
- The formula used is shown under each answer.
- Use “Copy result” to copy an answer.
How it works
Percentage change compares a new value with an old one, relative to the old value: (new − old) ÷ |old| × 100. Percentage difference compares two values without picking a starting point, relative to their average. The reverse calculator finds the value before a percentage was added — for example the price before tax.
Limitations
- A percentage change from zero is undefined, so it is reported as an error rather than shown as infinity.
Privacy
Your text is processed entirely in this browser tab. Nothing is uploaded, logged or saved by this tool.
Local processing protects your data from being uploaded, but it cannot protect against a compromised device or malicious browser extensions.