This discount calculator works out the sale price after a percent-off or amount-off discount. It also handles an extra discount on top (such as “an extra 10% off sale prices”), quantity and sales tax, and shows how much you really save.
How to calculate a discount
Sale price = original price × (1 − discount %)
Amount saved = original price − sale price
For an amount-off coupon, simply subtract the amount from the price.
Stacked discounts do not add up
When a store offers 25% off and then an extra 10% off, the second discount applies to the already reduced price. The total discount is 1 − (0.75 × 0.90) = 32.5%, not 35%.
Worked example
An $80 jacket at 25% off costs $60. An extra 10% off brings it to $54, a total saving of $26, or 32.5%.
Quick percent-off reference
| Discount | You pay | Example on $100 |
|---|---|---|
| 10% off | 90% | $90 |
| 20% off | 80% | $80 |
| 25% off | 75% | $75 |
| 30% off | 70% | $70 |
| 40% off | 60% | $60 |
| 50% off | 50% | $50 |
Frequently asked questions
How do I calculate 20% off a price?
Multiply the price by 0.8. For example, 20% off $45 is $45 × 0.8 = $36.
Is 50% off plus 20% off the same as 70% off?
No. The 20% applies to the reduced price, so the total is 1 − (0.5 × 0.8) = 60% off.
Is sales tax charged before or after the discount?
Usually after: you pay tax on the discounted price. Manufacturer coupons can be treated differently in some US states.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount). A $60 item that was 25% off originally cost $60 ÷ 0.75 = $80.
Which is better: a percent off or an amount off?
Work out both in money. A $20-off coupon beats 15% off on anything under about $133, because 15% of $133 is $20.
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Last reviewed: October 2026. This calculator is for education only and is not financial, tax or legal advice.