How to calculate a percentage
- Choose the type of calculation with the buttons above.
- Enter the two numbers each field asks for; use a period or a comma for decimals.
- The result appears instantly, with the formula used and your numbers filled in.
- Tap Copy result to take it to another app.
Formulas and examples
A percentage is a part out of every hundred. To find X% of a number, multiply the number by X and divide by 100: 15% of 200 is 200 × 15 ÷ 100 = 30. To find what percent one number is of another, divide one by the other and multiply by 100: 30 is 15% of 200.
To apply an increase, multiply by (1 + percentage ÷ 100): a price of 200 with a 21% increase becomes 242. For a discount, multiply by (1 − percentage ÷ 100): 150 with a 20% discount becomes 120, and you save 30.
Percent change compares two values: going from 80 to 100 is a 25% rise, but going from 100 to 80 is a 20% drop, because the starting point is different. And to get back to the original value after an increase you have to divide, not subtract: if a value reached 121 after a 21% increase, it was 100 before.
Things to keep in mind
- Results are shown with up to 6 decimal places; round them as you need.
- If the starting value or the total is zero, the tool warns you because the percentage can't be calculated.
- Subtracting the same percentage you added does not give back the original value: use "Value before an increase".
Frequently asked questions
How do I calculate the percentage of a number?
Choose "X% of a number", then enter the percentage and the number. The number is multiplied by the percentage and divided by 100.
How do I calculate a discount?
Choose "Discount or decrease", then enter the price and the discount percentage. You'll see the final price and how much you save.
How do I find the percent increase between two values?
Choose "Percent change" and enter the starting and final values. The tool divides the difference by the starting value and multiplies by 100.
Why doesn't going up and then down by the same percentage get me back to the same value?
Because each percentage is applied to a different value. If 100 goes up 20%, it reaches 120; going down 20% from 120 gives 96, not 100.
Are my numbers sent anywhere?
No. Everything is calculated in your browser and nothing is saved or sent.