Percentage calculator
Enter a percentage and a number. Instead of making you pick an operation first, we give you all four answers at once.
Your figures
Result
- The amount plus that percentage
- 302.50
- The amount minus that percentage
- 197.50
- If the amount were that percentage, the total would be
- 1,190.48
What we assume
- All four results are always calculated, so you do not have to choose the operation before knowing which one you need.
- Percentages above 100 and negative percentages are accepted.
- Results are shown to two decimal places; the calculation itself is not rounded.
How it is calculated
A percentage is a proportion out of a hundred. Working out X% of an amount
means multiplying it by X / 100:
result = amount x percentage / 100
The other three answers follow from that:
- Adding the percentage: useful for tax, a surcharge or a rise.
- Subtracting it: a discount or a drop.
- The total: the inverse. If you know an amount represents a certain percentage, this tells you of what total.
The most common mistake
Adding and then subtracting the same percentage does not bring you back to where you started. Raise 100 by 20% and you get 120; take 20% off 120 and you land on 96, not 100. The percentage applies to a different base each time.
An example
21% of 250 is 52.50. Adding it gives 302.50 and subtracting it gives 197.50. And if 250 were 21% of something, that total would be 1,190.48.
Frequently asked questions
How do I work out a percentage in my head?
10% is moving the decimal point one place left. From there: 20% is double that, 5% is half of it, and 1% is moving the point two places. So 21% is 10% + 10% + 1%.
Why does going up and then down by the same percentage not return the original number?
Because the second operation applies to the result of the first, which is already a different number. It is why a 50% discount followed by a 50% rise leaves the price 25% below where it started.
Can I use negative percentages?
Yes. Minus 10% is the same as subtracting 10%, and you will see it line up in the "plus that percentage" field.
Keep calculating
All tools →- Percentage change calculatorFrom one value to another, how much has it gone up or down in percent? And how many times one is of the other.
- Stacked discount calculator50% and then an extra 20% is not 70%. Here you see the real final price and the single discount you are actually being given.
- What percentage one amount representsTwo numbers, and we tell you what percentage the first is of the second. With the remainder and the ratio in plain language.
Updated on 2026-08-26. Calculations run in your browser; nothing you type is sent to a server.