Percentage Calculator is a free tool for the six percentage questions people actually ask: a percent of a number, what percent one number is of another, the change between two values, increasing or decreasing by a percent, and working backwards from a percentage to the original number. Choose a question, enter two numbers and the answer appears instantly. It runs in your browser and nothing is uploaded.
How to calculate a percentage
- Pick the question at the top, for example % of a number.
- Type the two values into the boxes — the labels change to match the question.
- Read the answer under Result, and press the copy button if you need it elsewhere.
- Switch to Reverse % when you know the part and the percentage but not the whole.
Worked examples
Twenty-five percent of 200 is 50, since 0.25 × 200 = 50. Fifty is 25% of 200, because 50 ÷ 200 × 100 = 25. A price going from 40 to 50 is a 25% rise, and going from 50 back to 40 is a 20% fall — the same 10 units, a different base. Increasing 200 by 10% gives 220, and if 50 is 25% of something, that something is 200.
The rise-and-fall trap
A share price rises 20% and then falls 20%, and people expect to be back where they started. They are not: 100 becomes 120, then 20% of 120 is 24, leaving 96. The second percentage always applies to the new, bigger number. The same maths explains why a 50% loss needs a 100% gain to recover. Use the% change mode to compare two figures honestly, and remember that a change from 40% to 50% is 10 percentage points but a 25% increase.
Everyday uses
Discounts (“30% off £80”), tax added to a net price, grade percentages, tips and markups all reduce to one of these six questions. For restaurant bills the Tip Calculator splits the total between people; for growth over years, compound interestis the percentage maths that compounds rather than applies once.
Frequently asked questions
How do I find a percentage of a number?
Divide the percentage by 100, then multiply by the number. So 25% of 200 is 0.25 × 200 = 50. Type both values into “% of a number” and the tool does it instantly.
Why can a 20% rise then a 20% fall leave less than you started with?
Because the two percentages use different bases. 100 plus 20% is 120; 20% of 120 is 24, so subtracting it gives 96, not 100. The second percentage is taken from the larger number.
What is the difference between percentage change and percentage points?
Percentage change compares a new value with the old one: 40 to 50 is a 25% rise. Percentage points describe a difference between two percentages: going from 40% to 50% is 10 percentage points, which is also a 25% change.
How do I work backwards from a percentage?
Use the reverse mode: if 50 is 25% of a number, divide 50 by 0.25 to get 200. That converts a discount price back to the original, or a score back to the total.
Last updated