Discount calculator
One discount is easy. Two stacked discounts are where shops and shoppers both get it wrong: 20% off, then another 10%, is 28% off, not 30%.
USD
%
%
You pay$200.00
- You save
- $50.00
- True combined discount
- 20.00 %
- What adding them would suggest
- 20.00 %
- Price after the first discount
- $200.00
- Original price
- $250.00
The formula
Successive discounts multiply: final = price × (1 − d₁) × (1 − d₂). The combined rate is 1 − (1 − d₁)(1 − d₂), which is always less than d₁ + d₂.
Worked example
250 with 20% off is 200. A further 10% off that is 180, so you saved 70 — a combined 28%, not the 30% that adding the two rates would suggest.
How to use it
- 1Enter the full price before any reduction.
- 2Leave the second field at zero for a single discount.
- 3Check whether the second discount applies to the already-reduced price or to the original, which changes the answer — this calculator assumes the former, as most offers do.
Questions people ask
Why isn't 20% plus 10% equal to 30%?
Because the second discount is taken off a smaller number. The 10% applies to 200, not to 250, so it saves 20 rather than 25.
Which order should the discounts go in?
It makes no difference to the final price — multiplication commutes. It can matter for tax or loyalty points, which are sometimes calculated at an intermediate step.
Last reviewed: 2026-10-20