Calculate any percentage in seconds
Percentages are everywhere — exam marks, shop discounts, salary raises, tax, interest rates, tips and statistics. This percentage calculator handles the four questions people actually ask: what is X% of a number, what percent is one number of another, what is the percentage change between two values, and what do you get when you add or subtract a percentage.
Choose the calculation, type two numbers and the answer appears immediately. The formula is shown under every result with your own numbers filled in, so you can check the maths or copy the method into homework or a report.
How to use the Percentage Calculator
- Pick the type of calculation at the top: “X% of Y”, “X is what % of Y”, “% change” or “Add / subtract %”.
- Type your two numbers. Commas are fine — 1,250 is read as 1250.
- For “Add / subtract %”, choose whether to increase or decrease the number.
- Read the answer in the result panel and the worked formula below it.
- Press “Copy result” to paste the answer anywhere.
Percentage Calculator features
Four calculators in one
Covers percentage of a number, percentage ratio, percentage change and percentage increase or decrease.
Formula with your numbers
Each answer shows the exact calculation used, which makes it easy to learn and to verify.
Handles decimals and negatives
Works with values like 0.5%, −12 or 1,000,000 and keeps up to six decimal places.
Instant results
No calculate button — the answer updates as you type.
Percentage formulas explained
X% of Y: divide the percentage by 100 and multiply by the number. 15% of 240 = 0.15 × 240 = 36.
X is what percent of Y: divide the part by the whole and multiply by 100. 30 out of 120 = 30 ÷ 120 × 100 = 25%.
Percentage change: 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%. A negative result is a decrease.
Add or subtract a percentage: multiply the number by (1 + p ÷ 100) to increase it, or by (1 − p ÷ 100) to decrease it. 200 increased by 10% = 200 × 1.10 = 220.
Everyday examples
| Question | Calculation | Answer |
|---|---|---|
| A 20% tip on a $45 bill | 0.20 × 45 | $9 |
| Scored 42 out of 50 in a test | 42 ÷ 50 × 100 | 84% |
| Rent went from 1,200 to 1,290 | (1,290 − 1,200) ÷ 1,200 × 100 | +7.5% |
| Price of 80 after a 25% discount | 80 × (1 − 0.25) | 60 |
| Salary of 50,000 plus a 6% raise | 50,000 × 1.06 | 53,000 |
Percentage change vs. percentage points
If an interest rate rises from 4% to 5%, it has gone up by 1 percentage point but by 25 percent (because 1 is 25% of 4). News reports often mix these up. Use the “% change” mode to get the relative change, and simple subtraction for the change in percentage points.
Also note that a percentage increase followed by the same percentage decrease does not return you to the start: 100 increased by 50% is 150, but 150 decreased by 50% is 75.
Percentage Calculator FAQ
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply it by the number. For example, 18% of 350 is 0.18 × 350 = 63. Choose the “X% of Y” mode and the calculator does this for you.
How do I find what percentage one number is of another?
Divide the first number by the second and multiply by 100. If you got 45 marks out of 60, that is 45 ÷ 60 × 100 = 75%.
How do I calculate percentage increase?
Use (new − old) ÷ old × 100. If a price rises from 40 to 50, the increase is (50 − 40) ÷ 40 × 100 = 25%.
Why can’t the old value be zero in percentage change?
Percentage change divides by the old value, and dividing by zero is undefined. Any growth from zero is mathematically an infinite percentage increase, so the calculator asks for a non-zero starting value.
How do I remove a percentage that was already added, like tax?
Divide by (1 + rate). If a price including 18% tax is 590, the price before tax is 590 ÷ 1.18 = 500. The GST and VAT calculators do this automatically.
Is the calculator accurate for large numbers?
Yes. It uses standard double-precision arithmetic, which is exact for everyday values and shows up to six decimal places.