Percentage Calculator
Percentage Calculator works out percentages, discounts, markups, and percentage change from the numbers you enter. There is no calculate button to press: the result appears the moment you type a value, and you can copy it with one click.
Result
Enter A and B to see what percent A is of B.
All calculations run entirely in your browser; the numbers you enter are never sent to any server.
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About Percentage Calculator
Percentage Calculator works out percentages, discounts, markups, and percentage change from the numbers you enter. There is no calculate button to press: the result appears the moment you type a value, and you can copy it with one click.
It has four modes for different jobs. Find percentage answers "what percent is A of B?" — the core percent calculation. Discount takes an original price and a discount rate and shows the final price and how much you save, so you can check a "30% off" deal in a second. Markup adds a rate on top of a price to show the total and the added amount, which also works for adding sales tax to a pre-tax price. Percentage change takes a before value and an after value and returns the percentage increase or decrease, handy for year-over-year and growth-rate checks.
All math is done with high-precision decimal arithmetic (big.js), so a calculation like "30% off 1,980" never produces rounding artifacts and you always get an exact final price. Half-width and full-width digits and thousands separators (1,980) are recognized automatically.
Every calculation runs entirely in your browser and the numbers you enter are never sent to a server. No sign-up or installation is required, and it works on both phones and computers.
How to use
- Use the mode switch at the top to choose Find percentage, Discount, Markup, or Percentage change.
- In Find percentage, enter the part (A) and the whole (B) to see what percent A is of B.
- In Discount, enter the original price and the discount rate to see the final price and how much you save — perfect for a percent-off deal.
- In Markup, enter the original price and the markup rate to see the total and the added amount, including pre-tax to tax-inclusive prices.
- In Percentage change, enter the before and after values to see the percentage change, along with whether it increased or decreased.
- Copy any result with the Copy button, or use Share URL to send a link that includes your inputs.
Use cases
- Shoppers checking the final price and savings on a '30% off' sale item.
- Quickly adding sales tax to a pre-tax price (a markup calculation).
- Working out completion rates, scores, or shares — what percent A is of B.
- Checking year-over-year or month-over-month percentage change in sales or traffic.
- Turning survey or test results into a percentage.
- Doing fee or commission percentage math on amounts of money without rounding errors.
Notes
- In Find percentage, the whole (B) cannot be 0 because you cannot divide by zero. Enter a non-zero value.
- In Percentage change, the before value cannot be 0, otherwise the percentage change is undefined. Enter a non-zero value.
- All math uses big.js decimal arithmetic, so multiplying and dividing prices or percentages never introduces floating-point rounding errors.
- Results are rounded to six decimal places for readability, so this tool is not intended for calculations that need more digits than that.
- The optional 'wari' (Japanese tenths) unit for discount and markup rates is shown only in the Japanese interface.
- Every calculation runs in your browser; the numbers you enter are never sent to a server.