How to use this calculator
A discount removes a fraction of the original price. For successive discounts, the second discount acts on the reduced price, so the rates cannot simply be added. Prices are currency-neutral: use the same currency throughout. Taxes, fees and store-specific rounding are outside this calculation.
Two discounts, step by step
| Stage | Calculation | Amount |
|---|---|---|
| Starting price | — | 200 |
| First discount | 200 × 25% | Save 50; remaining 150 |
| Second discount | 150 × 10% | Save 15; remaining 135 |
| Total savings | 200 − 135 | 65, or 32.5% |
The second rate applies to 150, not 200. Adding 25% and 10% would incorrectly suggest 35% off and a price of 130. The calculator's two-discount mode uses 200 × 0.75 × 0.90 = 135.
Recovering the original price
A sale price of 180 after 25% off is 75% of the original. Divide 180 by 0.75 to get 240. Adding 25% to 180 gives 225 and does not undo the discount, because it uses a different base.
Use increase and decrease for a general percentage adjustment. Use percentage change to find the discount rate when both the original and sale prices are known; a reduction appears as a negative change. Delivery, tax and retailer-specific rounding are outside this tool.
The formula
Worked examples
20% off 100
100 × 0.80 = 80; you save 20.
80 after 20% off
80 / 0.80 = 100, not 96.
20% off, then 10% off
100 × 0.80 × 0.90 = 72. The combined discount is 28%, not 30%.
Special cases & input limits
Discounts must lie between 0% and 100%, and prices cannot be negative. A 100% discount gives a sale price of zero. Recovering the original after 100% off is impossible: there is no unique original price.
Inputs support a decimal point and scientific notation, up to 30 significant digits and a magnitude of 10⁻²⁰ to 10³⁰, or zero. Select 0–12 display decimal places. Very small or large answers use scientific notation so a nonzero result is not displayed as zero.
A common mistake
Adding the discount percentage back to a sale price uses the wrong reference. Recover the original by division.
Content updated · Calculation methodology