1. Pick a mode
Pick the question you're solving: percent of a number, one number as a percent of another, or the percent change between two numbers.
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Percentage calculator
Calculate any percentage in your browser.
Mode
X% of Y =
30
Y + (Percent)
230
Y − (Percent)
170
Numbers are calculated in this browser tab. Nothing is uploaded.
How it works
2. Type the numbers
Type the two numbers. The result updates on every keystroke — no submit button.
3. Copy
Copy the result if you need it elsewhere. Nothing is sent to a server.
About the Percentage Calculator tool
The Percentage Calculator answers the three percentage questions people actually run into. "X% of Y" finds a part of a whole — handy for discounts, tips, and tax estimates. "X is what % of Y" turns two raw numbers into a share of the total. And "percent change from X to Y" measures growth or decline, returning a negative number when the value drops. Pick the mode, type two numbers, and the answer updates on every keystroke with no submit button.
It is the quick way to settle a sale price, a commission, a test score, a markup, or a month-over-month change without reaching for a spreadsheet formula. Each mode shows the simple arithmetic behind the result, so it doubles as a way to check your own working. The calculator runs entirely in your browser — the numbers you enter never leave the page — and it is free, needs no account, and keeps working offline after the first load.
Frequently asked questions
How is "% of" calculated?
`X% of Y` returns `(X/100) × Y`. So 15% of 200 is 30. Useful for discounts and tax estimates.
How is "what %" calculated?
`X is what % of Y` returns `(X / Y) × 100`. So 50 is 25% of 200. Useful for converting raw numbers into share-of-total.
How is "% change" calculated?
`% change from X to Y` returns `((Y − X) / X) × 100`. A negative result means a decrease. Useful for growth, price changes, savings.