Discount Calculator
- Updated
- Formula shown
- Free, no sign-up
Results
$120.00 with 25% off is $90.00: you save $30.00.
How to use the discount calculator
- Choose the type: a percentage off, a fixed amount off, stacked discounts, or working back from a sale price.
- Enter the original price and the discount. For stacked offers, enter each discount in the order it is applied.
- Add your sales tax rate if you want the amount you will pay at the till.
Discount formulas
Fixed discount: sale price = price − amount off; discount % = amount off ÷ price × 100
Stacked: sale price = price × (1 − d₁) × (1 − d₂) × …
Original price = sale price ÷ (1 − discount ÷ 100)
A second discount is taken off the already-reduced price, so stacked discounts multiply rather than add. Working backwards also needs division: if an item is 25% off, the sale price is 75% of the original, so you divide by 0.75. Adding 25% back to the sale price gives too little.
Worked examples
- Percentage off: 25% off $120.00 saves $30.00, so you pay $90.00.
- Fixed amount: $20.00 off $120.00 leaves $100.00, a discount of 16.67%.
- Stacked: 20% off $120.00 gives $96.00; another 10% off that takes $9.60 more, for $86.40. The combined discount is 28%, not 30%.
- Reverse: an item on sale for $90.00 at 25% off was originally $90.00 ÷ 0.75 = $120.00.
Stacked discounts: equivalent single discount
The order of percentage discounts doesn't change the result; 20% then 10% equals 10% then 20%.
| First discount | Then | Equivalent single discount | Price of a $100 item |
|---|---|---|---|
| 10% | 10% | 19% | $81.00 |
| 20% | 10% | 28% | $72.00 |
| 20% | 20% | 36% | $64.00 |
| 25% | 10% | 32.5% | $67.50 |
| 30% | 20% | 44% | $56.00 |
| 40% | 10% | 46% | $54.00 |
| 50% | 10% | 55% | $45.00 |
| 50% | 20% | 60% | $40.00 |
| 50% | 50% | 75% | $25.00 |
Shopping tips
- "Extra 10% off sale prices" applies to the already-reduced price. A 50% sale with an extra 10% off is 55% off, not 60%.
- Percentage vs dollar coupons. A percentage coupon is worth more on big purchases and a fixed coupon on small ones. On a $120.00 item, 15% off ($18.00) beats $15.00 off; on a $80.00 item it doesn't ($12.00).
- With a fixed coupon, order matters. Taking 25% off $120.00 and then $20.00 leaves $70.00; taking the $20.00 first and then 25% leaves $75.00. Percentage first is better for you; the store decides the order.
- Tax comes after the discount in most stores, so the discount also saves you the tax on the amount taken off.
- Multi-buy offers are smaller than they sound. "Buy one, get one half price" is 25% off the pair, and "buy two, get one free" is 33.33% off three items, but only if you wanted that many.
- Check the "was" price. A discount is only a saving if the original price was a real selling price.
For a quick percent-off lookup with a table of common percentages, use the percent off calculator. Sellers checking what a promotion does to profit can use the margin calculator, and the sales tax calculator adds tax to the final price.
Frequently asked questions
How do I calculate a discount?
Multiply the price by the discount percentage and divide by 100 to get the savings, then subtract. 25% off $120 saves $30, so the sale price is $90.
Is 20% off and then 10% off the same as 30% off?
No. The second discount is taken from the reduced price: $120 − 20% = $96, then $96 − 10% = $86.40. That is a 28% discount overall, compared with $84 for a single 30% discount.
How do I find the original price from a sale price?
Divide the sale price by 1 minus the discount as a decimal. An item on sale for $90 at 25% off was $90 ÷ 0.75 = $120. Adding 25% to $90 gives $112.50, which is wrong.
How do I work out the percentage of a fixed discount?
Divide the amount off by the original price and multiply by 100. $20 off a $120 item is a 16.67% discount.
Is sales tax charged before or after a discount?
In most stores the discount comes first and tax is charged on the reduced price. At 8% tax, a $90 sale price comes to $97.20 at the till, compared with $129.60 at full price.