Percentage Calculator
Choose a question, enter two numbers, and see the answer with the working.
- Convert
15%to a decimal:15 ÷ 100 = 0.15 - Multiply:
80 × 0.15 = 12 - 15% of 80 is 12
By Murugan Vellaichamy · Last checked · Formulas: see how it works · No ads, no sign-up
To find a percentage of a number, divide the percentage by 100 and multiply by the number: 15% of 80 is 0.15 × 80 = 12. To find what percent one number is of another, divide the part by the whole and multiply by 100: 12 out of 80 is 15%.
See also: How to calculate percentages · Every percentage formula · All calculators
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What is a percentage?
A percentage is a number of parts in each 100. The symbol % means “divided by 100”, so 25% is the same value as 25 ÷ 100, or 0.25. A percentage always compares a part with a whole.
Percentages make it easy to compare amounts that have different totals. A class where 18 of 24 students pass has a pass rate of 75%. A class where 22 of 30 pass has a pass rate of 73.3%. The percentages show at once which class did better.
The five questions this calculator answers
Most percentage problems are one of five types. Each tab of the calculator solves one type.
- What is P% of X? Multiply X by P, then divide by 100. A 15% tip on an $80 bill is 80 × 15 ÷ 100 = $12.
- Y is what percent of X? Divide Y by X, then multiply by 100. 45 marks out of 60 is 45 ÷ 60 × 100 = 75%.
- Y is P% of what? Divide Y by P, then multiply by 100. If 8 students are 25% of a class, the class has 8 ÷ 25 × 100 = 32 students.
- X increased or decreased by P%? Multiply X by 1 plus or minus P ÷ 100. A $120 price with a 20% increase is 120 × 1.20 = $144.
- What is the percent change from A to B? Subtract A from B, divide by A, then multiply by 100. A price that goes from $80 to $100 increases by 20 ÷ 80 × 100 = 25%.
Each answer shows the formula, your numbers in the formula, and the steps. Use the steps to check your own work, or to learn the method.
How to calculate percentages in your head
Start with 10% or 1% of the number. Then build the percentage that you need from these values.
| To find | Do this | Example: 60 |
|---|---|---|
| 10% | Move the decimal point one place to the left | 6 |
| 5% | Calculate 10%, then divide by 2 | 3 |
| 20% | Calculate 10%, then multiply by 2 | 12 |
| 25% | Divide the number by 4 | 15 |
| 1% | Move the decimal point two places to the left | 0.6 |
To find 15%, add 10% and 5%: for 60, that is 6 + 3 = 9. The order of the numbers is not important: 8% of 50 is the same as 50% of 8, which is 4.
How do you check an answer?
Do the calculation in the opposite direction. If 15% of 80 is 12, then 12 ÷ 80 × 100 must give 15%. Also compare the answer with the whole. A percentage less than 100% must give a part smaller than the whole.
Two mistakes cause most wrong answers. The first is division by the wrong number: in percent change, always divide by the old value. The second is reversal by subtraction: to find a price before 20% tax, divide by 1.20, and do not subtract 20%. The reverse percentage calculator does this type of question.
About this calculator
The results update while you type, and each tab keeps its own numbers. “Share link” copies a link that opens the same calculation, and “Download PDF” saves the answer with its steps. The calculations run in your browser. The site has no ads and no sign-up. For the method behind each formula, see how it works and the guide how to calculate percentages.
Common questions.
Divide the percentage by 100, then multiply by the number. 15% of 80 is 0.15 × 80 = 12. Use the “% of” tab above.
Divide the part by the whole, then multiply by 100. 12 out of 80 is 12 ÷ 80 × 100 = 15%. The whole is the total that you compare against, not always the larger number.
A percentage point is the plain difference between two percentages. A rate that goes from 40% to 44% goes up 4 percentage points. As a percent change, that is a 10% increase in the rate.
Yes. “Share link” copies a link that opens the same calculation. To put the calculator on your own site, copy the embed code at the bottom of this page.
Yes. There is no sign-up and there are no ads. The calculations run in your browser, so the numbers that you enter are not sent to our server.