Discount formulas
Sale price = original price × (1 − discount ÷ 100)
Two discounts: price × (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100)
Original price = sale price ÷ (1 − discount ÷ 100)
Quick mental math for sales
- 10% off: move the decimal point one place left and subtract. $45 → $4.50 off → $40.50.
- 25% off: take a quarter off. $80 → $20 off → $60.
- 50% off: half price.
- “Buy one, get one 50% off”: on two equal items, that's 25% off the pair.
More shortcuts in our guide to calculating percentages in your head.
Frequently asked questions
How do I calculate a discount?
Multiply the original price by the discount percentage and divide by 100 to get the savings, then subtract that from the price. 25% off $80 is $20 off, so you pay $60. A quicker way is to multiply by (100 − discount) ÷ 100: $80 × 0.75 = $60.
Is 30% off plus an extra 10% the same as 40% off?
No. The second discount applies to the already-reduced price. 30% off $100 is $70, and an extra 10% off $70 is $63, which is a 37% total discount, not 40%.
Is sales tax charged before or after the discount?
In the US, sales tax is normally charged on the discounted price you actually pay, so this calculator adds tax after the discounts. Manufacturer coupons can be an exception in some states.
How do I find the original price from the sale price?
Divide the sale price by (1 − discount ÷ 100). If a jacket costs $60 after 25% off, the original price was 60 ÷ 0.75 = $80.