How to calculate a discount
A discount is a percentage taken off the original price. To find the sale price, multiply the price by what is left after the discount:
Example: a $80 jacket at 25% off costs 80 × 0.75 = $60, so you save $20. A quick mental trick: 10% is the price with the decimal point moved one place left ($8), so 20% is double that ($16) and 5% is half ($4).
Stacked discounts: 20% + 10% is not 30%
When a store offers “an extra 10% off sale prices”, the second discount applies to the already reduced price. The discounts multiply rather than add:
On a $100 item, 20% off gives $80, and another 10% off gives $72. That is a total discount of 28%, not 30%. Similarly, 50% + 20% is 60% off in total, not 70%. Use the “extra discount” box above to see the true figure.
How to find the discount percentage
Example: a TV that was $250 and is now $180 is (250 − 180) ÷ 250 × 100 = 28% off.
How to find the original price
Example: you paid $45 after a 40% discount, so the original price was 45 ÷ 0.60 = $75. Note that adding 40% back to $45 gives $63, which is wrong: the percentage was taken from the original price, not the sale price.
Common deals in percentage terms
- Buy one, get one free = 50% off each item, but only if you want both.
- Buy 2, get the second half price = 25% off the pair.
- 3 for the price of 2 = 33.3% off each item.
- “Up to 70% off” usually means only a few items get the full 70%.
Sales tax is normally added after the discount; see the sales tax calculator for your state's rate. For other percentage questions use the percentage calculator.
Frequently asked questions
How do I calculate 20% off a price?
Multiply the price by 0.80. For example, 20% off $60 is 60 × 0.80 = $48, and you save $12.
Is 20% off plus an extra 10% off the same as 30% off?
No. The extra 10% applies to the already reduced price, so the total discount is 1 − 0.80 × 0.90 = 28%. On a $100 item you pay $72, not $70.
How do I work out the percentage discount between two prices?
Subtract the sale price from the original price, divide by the original price and multiply by 100. From $50 down to $35 is (50 − 35) ÷ 50 × 100 = 30% off.
How do I find the original price before a discount?
Divide the sale price by 1 minus the discount. If you paid $63 after 30% off, the original price was 63 ÷ 0.70 = $90.
Is sales tax calculated before or after the discount?
In most US states, sales tax is charged on the discounted price for store discounts and coupons from the store. Manufacturer coupons are sometimes taxed on the full price, depending on the state.
Results are rounded to two decimal places. Check the final price at checkout, as stores may round differently.