Percentage Calculator
Work out percentages, increases, decreases, and ratios.
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All 93 toolsWhat is the Percentage Calculator?
A percentage calculator answers the everyday math you run into constantly: what is 25% of 200, what percentage is one number of another, and how much something changed in percentage terms. Type your numbers and get the answer immediately — no formula to remember, no mental arithmetic, no risk of slipping a decimal point.
Percentages show up everywhere: discounts and sales tax, tips, exam scores, interest, statistics, and tracking changes over time. The underlying math is simple but easy to get backwards under pressure, especially the difference between “X is what percent of Y” and “what is X percent of Y.” This tool keeps the two straight and shows both at once.
It runs entirely in your browser, so it is instant, works offline once loaded, and never sends your numbers anywhere.
How to calculate a percentage
- 1
To find a percentage of a number, enter the percentage and the total — for example, 25% of 200 — and read the result.
- 2
To find what percentage one number is of another, the tool also shows that relationship for the same two values.
- 3
Change either field and the answers recalculate instantly, so you can run several quick checks in a row.
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Copy the result you need, or use it as a step in a larger calculation like a discount or a tax figure.
Why keep a percentage calculator handy
Both directions at once
See “what is X% of Y” and “X is what % of Y” together, so you never solve the wrong one.
No formula needed
Skip the mental math and decimal-shuffling — just type the numbers and read the answer.
Great for money tasks
Discounts, tips, tax, and interest all start with a percentage; this is the fast first step.
Instant and private
Answers update as you type, and nothing you enter leaves your browser.
The percentage formulas behind the tool
A percentage is just a fraction of 100. To find a percentage of a number, multiply the number by the percentage divided by 100: 25% of 200 is 200 × (25 ÷ 100) = 50. To find what percentage one value is of another, divide the part by the whole and multiply by 100: 50 out of 200 is (50 ÷ 200) × 100 = 25%.
Percentage change is a third common case and a frequent source of errors. The formula is (new − old) ÷ old × 100. A move from 120 to 150 is (150 − 120) ÷ 120 × 100 = 25% increase; reversing it from 150 to 120 is a 20% decrease — not 25% — because the starting point changed. Knowing which value is the “old” one is the whole trick.
These three operations cover the vast majority of real-world percentage questions. For dedicated workflows we also offer a discount calculator, a sales-tax calculator, and a percentage-change calculator, each tuned to a specific task while using the same underlying math.