Discount Calculator
Find the sale price after a percentage discount, including stacked extra discounts and sales tax.
How to calculate a discount
Multiply the original price by the discount rate to get the amount saved, then subtract it. Or multiply the price by (1 − discount) in one step.
Sale price = Price × (1 − Discount% ÷ 100)
Stacked discounts do not add up
"25% off plus an extra 20% off" is not 45% off. The second discount applies to the already-reduced price:
$120 × 0.75 = $90 after the first discount. $90 × 0.80 = $72 after the second. The total saving is $48, which is 40% off, not 45%.
The combined discount is 1 − (1 − a)(1 − b). For 25% and 20% that is 1 − 0.75 × 0.80 = 0.40.
Shopping tips
- Compare the final price, not the percentage. 30% off a $100 item ($70) costs more than 10% off a $70 item ($63).
- Check the unit price on multi-buy offers with the unit price calculator.
- Sales tax is usually charged on the discounted price, which this calculator applies.
Frequently asked questions
How do I calculate 30% off?
Multiply the price by 0.70. For example, 30% off $80 is $80 × 0.70 = $56, a saving of $24.
Are two discounts of 20% the same as 40% off?
No. Two 20% discounts give 1 − 0.8 × 0.8 = 36% off in total, because the second discount applies to the reduced price.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount). If an item costs $60 after 25% off, the original price was $60 ÷ 0.75 = $80.
Last reviewed Oct 20, 2026. Results are estimates; check important decisions with a qualified professional.