Percentage calculator
Fill in the two numbers in whichever sentence matches your question. Answers update as you type.
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Percentage formulas
X% of Y is X ÷ 100 × Y. 20% of 150 is 0.2 × 150 = 30.
X is what percent of Y is X ÷ Y × 100. 30 out of 150 is 20%.
Percent change from A to B is (B − A) ÷ |A| × 100. Going from 50 to 75 is a 50% increase; going from 80 to 60 is a 25% decrease. The change is measured against the starting number, so going back from 75 to 50 is a 33.3% decrease, not 50%.
The whole from a part is X × 100 ÷ P. If 30 is 20% of something, the whole is 150.
Everyday examples
| Question | Which sentence to use | Answer |
|---|---|---|
| An 18% tip on a $64.50 bill | What is 18 % of 64.50? | $11.61 |
| A $80 jacket at 25% off | What is 25 % of 80? Then subtract | Save $20, pay $60 |
| 8.25% sales tax on $49.99 | What is 8.25 % of 49.99? | $4.12 (rounded) |
| 42 out of 56 on a test | 42 is what percent of 56? | 75% |
| A share price going from $120 to $150 | From 120 to 150 | +25% |
| You paid $68 after 15% off. What was the full price? | 68 is 85 % of what? | $80 |
The last row is the one people get wrong most often. After 15% off you paid 85% of the price, so the original is 68 ÷ 0.85 = 80, not 68 plus 15%.
Discounts and increases in one step
The top line of the calculator, "[80] minus [20] % =", takes the percent off (or adds it on) in one go and shows the difference underneath, so you don't have to subtract yourself. Switch minus to plus for tax, a raise or a markup. These are the answers it gives:
| You type | Answer | Line under it |
|---|---|---|
| 80 minus 20 % | 64 | You save 16 · 80 × (1 − 20%) |
| 1,250 minus 12.5 % | 1,093.75 | You save 156.25 |
| 1,800 plus 5 % (rent increase) | 1,890 | That adds 90 |
| 52,000 plus 3.5 % (pay raise) | 53,820 | That adds 1,820 |
| 64.50 plus 18 % (tip) | 76.11 | That adds 11.61 |
| 110 minus 10 % | 99 | You save 11 |
The last row is the second half of the "up 10%, down 10%" example below: 100 plus 10% is 110, and 110 minus 10% is 99, not 100. You can paste amounts straight from a receipt or a price tag: $80, €1.250,50, £1,250 and 12.5% are all read as numbers. Spaces are ignored, so "1 250" is 1250. If something can't be read, such as a word or a stray letter, the line under the answer asks for just the number.
Mistakes to watch for
Ups and downs don't cancel out. A price that rises 10% and then falls 10% ends up 1% lower: 100 becomes 110, and 10% of 110 is 11, leaving 99. Each change is measured from a different starting number.
Reversing a change is not the same percentage. From 120 to 150 is a 25% rise, but from 150 back to 120 is a 20% fall.
Percent of a percent. A 20% discount on top of a 10% discount is not 30% off. You pay 90% and then 80% of that, which is 72% of the price, so the total saving is 28%.
Percent versus percentage points. A rate going from 4% to 5% is a rise of 1 percentage point, or a 25% increase. News stories often mix the two.
Doing it without a calculator
10% of any number is that number with the decimal point moved one place left: 10% of 64.50 is 6.45. From there, 5% is half of that, 20% is double, and 15% is 10% plus 5%. For 1%, move the decimal point two places. At a restaurant, the tip calculator does the tip and splits the bill in one go.
Questions
What is the difference between percent change and percentage points?
If an interest rate goes from 4% to 5%, it rose by 1 percentage point, but by 25% as a percent change. This calculator gives the percent change; subtract the two rates yourself for points.
How do I work out percent off a price?
Use the top line: "80 minus 25 %" gives what you pay, 60, and the line under it says you save 20. If you'd rather see the saving first, "What is 25 % of 80" gives 20.
Can I type commas, a % sign or a currency symbol?
Yes. "1,250", "12.5%", the European style "12,5" and amounts with $, €, £, ¥ or ₩ in front all work. Negative numbers and decimals are fine too.