What is a discount calculator?
A discount calculator turns “25% off” into a real price. It is handy when you are shopping in a sale, comparing offers between stores, checking a receipt, or setting promotional prices for your own shop. Enter the original price and the percentage off, and it shows the price you pay and the amount you save.
Many promotions stack: “an extra 10% off sale prices” or a coupon on top of a seasonal discount. Stacked discounts are applied one after another, not added together, so 25% plus 10% is a 32.5% total discount, not 35%. This calculator applies them in order and shows the true combined discount.
How to use it
- Enter the original price before any discount.
- Enter the discount percentage.
- Optionally add an extra discount, such as a coupon applied to the sale price.
- Optionally add sales tax if it is charged at the till.
- Read the final price, your savings and the effective total discount.
Formulas
Sale price = Price × (1 − D₁ ÷ 100) × (1 − D₂ ÷ 100)
Savings = Price − Sale price
Final price = Sale price × (1 + Tax ÷ 100)
Tax is applied to the discounted price, which is how sales tax works in most places. The total discount percentage is the savings divided by the original price.
Examples
Single discount: a 200 jacket at 25% off costs 200 × 0.75 = 150, saving 50.
Stacked discount: with an extra 10% off the sale price, the jacket costs 150 × 0.90 = 135. You save 65, a total discount of 32.5%.
With tax: add 8% sales tax and you pay 135 × 1.08 = 145.80 at the till.
More worked examples
With sales tax: an $80 jacket at 30% off costs $56. With New York City's 8.875% sales tax added at the till, you pay $60.97.
Common mistakes to avoid
- Adding stacked discounts together. 20% plus 10% off is 28% in total, not 30%, because the second discount applies to the reduced price.
- Forgetting tax. In many US states the shelf price excludes sales tax, so the till price is higher.
- Judging a deal by the percentage alone. Compare the final price across stores. To work out percentages in general, use the percentage calculator.
Sources and methodology
The calculations on this page follow these published standards and references. The code is covered by automated tests against known values.
- Standard percentage arithmetic