Percentage Calculator
Work out percentages, percentage of a value and percent changes.CalculatorsPercentage calculator
Four common percentage calculations in one place. Results are computed as you click Calculate.
What is X% of Y?
About this tool
Four questions cover almost every everyday percentage problem: what percent is X of Y, what is P percent of Y, what happens when a value increases or decreases by P percent, and the percent change from A to B. Each mode takes two numbers and gives a single result, with clear errors for undefined cases.
How to use the Percentage Calculator tool
- Choose a mode. Pick one of four modes: % of a value, What percent, Increase / decrease, or % change.
- Enter the numbers. Fill in the two values shown for that mode. Invalid or zero denominators are reported.
- Read the result. Click Calculate. The answer appears in a highlighted panel; undefined cases are explained instead of showing Infinity.
Supported formats
Input
- Two numeric values
Output
- Percentage
- Resulting value
- Clear error for undefined cases
Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.
Frequently asked questions
Can I use decimal values?
Yes. Any finite number is accepted, including decimals and negative values.
What happens if I divide by zero?
Dividing by zero is undefined in the What percent and % change modes; the tool explains why instead of returning Infinity.
How is a decrease handled?
Use the Increase / decrease mode and pick Increase or Decrease. The percentage is applied to the base value.
Are results rounded?
The result is shown with full floating-point precision; no currency or rounding rules are applied.
Privacy
Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.
No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.
Known limitations
- Division by zero is rejected rather than returning an infinite value.
- Results are shown with full floating-point precision, which may include long decimals.
- Currency formatting and rounding rules are not applied.
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