Percentage Calculator
Work out percentages, ratios, and percent changes.
To answer "what is X% of Y", this percentage calculator divides X by 100 and multiplies by Y — so 20% of 150 is 30. Pick a mode and type two numbers to also find what percent one value is of another or the percent increase or decrease between them; the answer appears instantly in your browser, with no sign-up and nothing uploaded.
Read the guide: Percentage Points vs. Percent: The Difference That Costs MillionsAbout the Percentage Calculator
Percentages come up everywhere — discounts, tips, test scores, tax, and growth rates. This calculator handles the three questions people ask most, each on its own tab: what is X% of a number, what percent one number is of another, and the percentage increase or decrease from one value to another.
Pick a mode, type your two numbers, and the answer updates instantly (rounded to four decimals and formatted with thousands separators). No formulas to remember, and nothing is sent anywhere — the math runs right in your browser.
How to use it
- 1Choose a mode. Select “% of a number”, “X is what % of Y”, or “% increase / decrease”.
- 2Enter two numbers. Fill in the two values the chosen mode asks for.
- 3Read the result. The answer appears instantly below, formatted for readability.
Frequently asked questions
How do I calculate a percentage online?+
Pick one of the three modes, type your two numbers, and the result appears instantly below — no formula to memorise and no sign-up. The math runs entirely in your browser, so nothing is sent to a server.
What is X percent of Y?+
Choose the “% of a number” mode, enter the percent as X and the number as Y, and the calculator returns (X ÷ 100) × Y — for instance, 15% of 200 is 30.
How do I calculate a percentage of a number?+
Use the “% of a number” mode: it computes (X ÷ 100) × Y. For example, 20% of 150 is (20 ÷ 100) × 150 = 30.
How do I find what percent one number is of another?+
Use the “X is what % of Y” mode: it computes (X ÷ Y) × 100. For example, 30 is (30 ÷ 150) × 100 = 20% of 150.
How is the percentage increase or decrease worked out?+
The “% increase / decrease” mode takes a from and a to value and computes ((to − from) ÷ from) × 100. Going from 80 to 100 gives a 25% increase.
What does a negative result mean in percent change?+
A negative percentage means the value went down. From 100 to 80 gives −20%, a 20% decrease.
Why does the result sometimes show a dash?+
A dash (—) appears when the result is not a finite number, for example dividing by zero when the “of” value or the starting value is 0.
Is anything uploaded?+
No. The calculation happens entirely in your browser with no sign-up and nothing sent to a server.
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