Percentage Calculator
Find a percentage of a number, a ratio, or a percentage change.
Result
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Tip: switch modes above to reverse the calculation.
Three ways to use this calculator
Percentages describe a part out of one hundred. This tool covers the three questions people ask most often.
| Percent of a number | 15% of 200 = (15 ÷ 100) × 200 = 30 |
|---|---|
| X is what percent of Y | 30 is what percent of 200? (30 ÷ 200) × 100 = 15% |
| Percentage change | From 200 to 250 is ((250 − 200) ÷ 200) × 100 = +25% |
Worked example
To find 15% of 200, multiply 200 by 0.15 to get 30. Going the other way, 30 out of 200 is 30 divided by 200 times 100, which is 15%.
Where percentages catch people out
Percentages turn up everywhere — sales, tips, interest, statistics — but a couple of quirks trip people up. The most common is treating a rise and the matching fall as equal: a number that drops 20% needs a 25% gain to get back, because each percentage is taken from a different starting point.
Two distinctions worth knowing
- Percentage vs percentage points. Going from 10% to 12% is two percentage points, but a 20% relative increase.
- Order doesn't undo itself. Adding 10% and then removing 10% leaves you slightly below where you started.
Frequently asked questions
How do I add a percentage to a number?
Multiply by 1 plus the percentage as a decimal. Adding 20% to 50 is 50 times 1.20, which is 60.
How do I work out a percentage decrease?
Subtract the new value from the old, divide by the old value, then multiply by 100. A drop from 250 to 200 is a 20% decrease.
Why don't stacked discounts simply add up?
They multiply rather than add. 25% off then 20% off is 0.75 times 0.80, which is 0.60 — a 40% reduction overall, not 45%.
What is the difference between percent and percentage points?
Going from 10% to 12% is a rise of 2 percentage points, but in relative terms it is a 20% increase.