Guides
How this percentage calculator works
A short and checkable description of what happens when you type numbers.
The page reads your numbers, applies the formula for the calculation you chose, cleans the result of floating point artifacts, and shows it with the working. It all runs in your browser and nothing is sent.
Formulas
- Percent of a number: percent / 100 x number.
- What percent: X / Y x 100.
- Increase or decrease: number x (1 + or - percent / 100).
- Percentage change: (end - start) / |start| x 100.
- Discount: saved = price x percent / 100, final = price - saved.
- Reverse: result / (1 + or - percent / 100).
Numbers and rounding
Computers store decimals in binary, which can turn 0.1 + 0.2 into 0.30000000000000004. Results are cleaned to 12 significant digits first, so those artifacts never appear. Results are shown with up to six decimal places and are not rounded for further calculation.
Typing numbers
Use the decimal mark of your language. Spaces are ignored. Thousands separators are understood when they make sense, and anything that is not a plain number gives a message instead of a result.
Privacy
- Your numbers are not sent to a server and are not stored.
- Analytics, if you accept it, counts page visits and never receives your numbers.
Frequently asked questions
Can I trust the results for money?
The arithmetic is exact to the digits shown, but the tool does not apply the rounding, tax and fee rules of your situation. Check important results yourself.