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Does it work on my phone?
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Percentage Calculator
Six percentage calculators in one: X% of Y, what percent, percentage increase or decrease, difference, add/subtract a %, and reverse percentage — with steps.
Every everyday percentage question in one place: work out 20% of 150, find what percent 30 is of 150, see how much a price went up or down, compare two numbers, add tax or take off a discount, or find the original price before a change. Results update as you type, and each answer shows the formula and the steps so you can check it — or learn how to do it yourself.
How to use Percentage Calculator
- Find the calculator that matches your question.
- Type your numbers into the boxes in the sentence.
- Read the answer straight away, with the working shown below it.
- Use a negative percentage to subtract, e.g. −20 for a 20% discount.
Features
- X% of Y — for tips, discounts, commissions and tax.
- X is what percent of Y — for scores, shares and progress.
- Percentage change — increase or decrease from an old to a new value.
- Percentage difference — comparing two values with no “before” and “after”.
- Add or subtract a percentage — prices with VAT or sales tax, discounts, raises.
- Reverse percentage — the original value before a percentage change.
- Formula and steps shown for every answer; works on phones.
Percentage formulas
All percentage problems use one of these formulas.
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | X ÷ 100 × Y | 20% of 150 = 30 |
| X is what % of Y? | X ÷ Y × 100 | 30 is 20% of 150 |
| % change from A to B | (B − A) ÷ |A| × 100 | 80 → 100 = +25% |
| % difference of A and B | |A − B| ÷ ((A + B) ÷ 2) × 100 | 80 and 100 = 22.2% |
| Y plus X% | Y × (1 + X ÷ 100) | 250 + 15% = 287.5 |
| Original before +X% | result ÷ (1 + X ÷ 100) | 115 after +15% was 100 |
Percentage change vs percentage difference
Percentage change has a direction: it compares a new value with an old one, so going from 80 to 100 is a 25% increase, while going from 100 to 80 is a 20% decrease. Percentage difference has no direction: it compares two values by their average, so 80 and 100 differ by 22.2% whichever comes first. Use change for prices, salaries and growth over time; use difference to compare two measurements, products or quotes.
Why a 20% rise and a 20% fall don't cancel out
Percentages are taken of different starting values. A price of 100 that rises 20% becomes 120; a 20% fall from 120 is 24, leaving 96. Likewise, to undo a 20% discount you need a 25% increase. The reverse percentage calculator answers the common question “this costs 115 including 15% tax — what was the price before tax?” (100, not 97.75).
Percentage points vs percent
When a rate goes from 4% to 5%, it rose by 1 percentage point — but by 25 percent, because 1 is a quarter of 4. News about interest rates, election results and unemployment often mixes these up. Use percentage change on the two rates to get the percent change.
Frequently asked questions
How do I work out a tip or a discount?
For a 15% tip on 64, use “What is X% of Y?” with 15 and 64 (9.6), or “Add or subtract a percentage” with 64 and 15 to get the total (73.6). For a 30% discount, enter the price and −30.
How do I calculate a percentage of a percentage?
Multiply them as fractions: 50% of 20% is 0.5 × 0.2 = 0.1, which is 10%. With the first calculator, enter 50 and 20 to get 10.
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 150 = 0.2 × 150 = 30. Use the first calculator.
How do I calculate a percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25%.
How do I take a percentage off a price?
Use “Add or subtract a percentage” with a negative percentage: 250 with −20% gives 200.
How do I find the price before tax?
Use reverse percentage: enter the price including tax and the tax rate. 115 including 15% tax was 100 before tax.
Can percentages be more than 100?
Yes. A value can be 150% of another, and something that triples has increased by 200%.
Why can't the percentage change be calculated from 0?
Any increase from 0 is infinitely large in percentage terms, so the change is undefined. Report the absolute change instead.