Percentage Calculator
Work out percentages in seconds — find X% of a number, see what percent one value is of another, reverse a percentage, measure the change between two values, or add and subtract a percent. The result updates live as you type.
How to use
Pick a mode
Choose one of five modes: percent of a number, what percent one number is of another, reverse percentage, change from A to B, or add / subtract a percent.
Enter the values
Type the numbers into the fields. Decimals and comma separators are accepted.
Read the live result
The answer updates as you type — there is no Calculate button.
Check the formula
Every result shows the formula with the substituted values, so you can verify the math.
Share or bookmark
The current mode and values are stored in the URL — copy the link to reopen the same setup later.
Features
Five calculation modes
Percent of a number, what percent one number is of another, reverse percentage, percentage change, and add / subtract a percent.
Live calculation
Results update on every keystroke — there is no Calculate button to press.
Shows the formula
Each result includes the formula with substituted values so you can verify the math.
Shareable links
The current mode and values are captured in the URL, so you can bookmark or send the exact setup.
Decimals and large numbers
Accepts up to four decimal places and values in the millions.
Runs in your browser
All math happens on the client — nothing is sent to a server.
Common use cases
- Check the real discount on a sale tag before buying
- Split a restaurant bill and work out the tip
- Extract the VAT portion from a gross invoice amount
- See how much a price or metric grew between two periods
- Reverse a percentage to find the original price before a discount