How to calculate a discount
To find a sale price, multiply the original price by (1 − discount ÷ 100). For 30% off an $80 item: $80 × 0.70 = $56, and you save $24. This calculator shows the sale price, the dollar amount saved, and the total effective discount.
Stacked discounts are not additive
Stores often advertise deals like "30% off, plus an extra 20% at checkout." It's tempting to think that's 50% off, but the second discount applies to the already reduced price. On $80, 30% off gives $56, and an extra 20% off $56 gives $44.80. The real discount is 44%, not 50%. Enter the second discount in the "Extra discount" field to see the true final price.
The general formula is: final = price × (1 − d₁) × (1 − d₂). The order of the two discounts doesn't change the result.
Quick mental math
- 10% off: subtract one-tenth of the price.
- 25% off: pay three-quarters of the price.
- 50% off: pay half.
- "Buy one, get one 50% off": 25% off each item when both cost the same.
Shopping smarter
A big percentage off is only a good deal if the original price is fair. Retailers sometimes inflate "compare at" prices, so check price history or competitors. Also remember that sales tax is normally calculated on the discounted price; use our sales tax calculator to find your total at checkout. Coupons for a fixed dollar amount (like $10 off $50) are worth more on cheaper items as a percentage.
Working backward
If you know the sale price and the discount, divide to get the original: a $56 price after 30% off was originally $56 ÷ 0.70 = $80.
Frequently asked questions
How do I calculate 20% off?
Multiply the price by 0.80. For example, 20% off $50 is $40.
Is 30% + 20% the same as 50% off?
No. Stacked discounts multiply: 30% then 20% off equals 44% off in total.
Is sales tax applied before or after the discount?
Usually after. Tax is charged on the discounted price in most U.S. states.