Percentage Calculator
Six quick percentage calculators in one place: percent of a number, what percent one number is of another, percentage change, increase or decrease by a percent, and more.
Percentage of a number
Discounts, tips, tax and commission.
What percent is it?
Test scores, shares and proportions.
Percentage change
Price changes, growth and salary raises.
Increase or decrease by %
Sale prices, markups and adding tax.
Percentage difference
Compare two values when neither is the “original”.
Find the original number
Work back from a part you already know.
Calculated in your browser. Nothing is sent anywhere.
The formulas behind each calculator
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | X ÷ 100 × Y | 15% of 200 = 30 |
| X is what % of Y? | X ÷ Y × 100 | 45 of 60 = 75% |
| Change from X to Y | (Y − X) ÷ X × 100 | 50 → 65 = +30% |
| Y increased by X% | Y × (1 + X ÷ 100) | 80 + 25% = 100 |
| Y decreased by X% | Y × (1 − X ÷ 100) | 80 − 25% = 60 |
| Difference between X and Y | |X − Y| ÷ average × 100 | 40 and 60 = 40% |
| X is P% of what? | X ÷ (P ÷ 100) | 30 is 20% of 150 |
Percentage change vs percentage difference
Use percentage change when one value clearly came first, like an old price and a new price. Use percentage difference when you are comparing two values side by side, like the prices at two shops. Then neither is the starting point, so the difference is measured against their average.
Why +50% then −50% does not get you back
Percentages apply to whatever the number is at the time. If a price of 100 rises 50% it becomes 150. If it then falls 50%, it drops by half of 150, landing at 75, not 100. This is why a 50% loss on an investment needs a 100% gain to recover.
Percent vs percentage points
If an interest rate rises from 4% to 5%, it went up by 1 percentage point, but by 25 percent of its old value. News reports and loan offers often mix these up, so check which one is meant.
Percentage Calculator FAQs
Quick answers to everyday percentage questions.
How do I calculate a discount?+
Use “Increase or decrease by %” set to Decrease. A 25% discount on 80 gives 60. To see only the amount you save, use “Percentage of a number”: 25% of 80 is 20.
How do I add tax or VAT to a price?+
Use “Increase or decrease by %” set to Increase. A price of 200 plus 17% tax is 234.
How do I remove tax from a price that already includes it?+
Divide the total by 1 plus the tax rate. For a total of 234 with 17% tax: 234 ÷ 1.17 = 200 before tax.
Why can’t I calculate a percentage change from 0?+
Percentage change compares the new value with the old one. When the old value is 0 there is nothing to compare against, so the change is undefined.
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