Sale price and savings from a percent-off or double discount.
Shops rarely show you the final price, so a discount calculator does the sum for you. Enter the original price and the percentage off, and it shows the sale price, how much you save and the effective discount. It also handles the “extra 10% off sale prices” kind of offer, which is never as big as it sounds, and can add sales tax so you see what you will actually pay at the till.
How to Use the Discount Calculator
- Original price: the price before any discount.
- Discount: the percentage off, such as 25.
- Extra discount (optional): a second percentage taken off the already reduced price, such as “an extra 10% off”.
- Sales tax (optional): your local tax rate, if tax is added at checkout.
The results show the sale price, the amount you save, the effective discount and, if you entered tax, the final price with tax. A chart shows how much of the original price you pay and how much you save.
The Discount Formula
- Sale price = Original price × (1 − Discount ÷ 100)
- Amount saved = Original price − Sale price
- With a second discount: Sale price = Original × (1 − D1 ÷ 100) × (1 − D2 ÷ 100)
Discount Examples
25% off $80.
80 × 0.75 = $60. You save $20.
Stacked discounts: 25% off, then an extra 10% off.
First discount: 80 × 0.75 = $60. Extra 10% off the sale price: 60 × 0.90 = $54. You save $26, an effective discount of 32.5%, not 35%.
Adding tax. With 8% sales tax added to the $54 sale price: 54 × 1.08 = $58.32 at the till.
30% off $249.99.
249.99 × 0.70 = $174.993, which rounds to $174.99. You save $75.00.
Quick Discount Table
To find a sale price in one step, multiply the original price by the number in the middle column.
| Discount | Multiply the price by | Sale price of a $60 item |
|---|---|---|
| 10% off | 0.90 | $54.00 |
| 15% off | 0.85 | $51.00 |
| 20% off | 0.80 | $48.00 |
| 25% off | 0.75 | $45.00 |
| 30% off | 0.70 | $42.00 |
| 40% off | 0.60 | $36.00 |
| 50% off | 0.50 | $30.00 |
| 70% off | 0.30 | $18.00 |
Why Stacked Discounts Are Smaller Than They Look
The second discount is taken off the reduced price, not the original. So 25% off plus an extra 10% off is not 35% off. You pay 75% of the price, then 90% of that: 0.75 × 0.90 = 0.675, which means you pay 67.5% and save 32.5%.
The bigger the discounts, the bigger the gap. “50% off, plus an extra 50%” sounds like free, but it is 75% off: you pay a quarter of the price.
Checking Whether a Deal Is Real
- Compare against the usual price, not the “was” price. A discount is only a saving if the item normally sells at the original price.
- Compare the final price, including delivery. A smaller discount with free shipping can beat a bigger one without it.
- Buy one, get one half price is 25% off, not 50%. Two $40 items cost $60 instead of $80.
- Multi-buy offers only save money if you need the extra items.
When to Use a Different Calculator
- Know the sale price and the percentage off, but not the original price? Use the reverse percentage calculator.
- Know the old and new price and want the percentage off? The percentage change calculator shows it as a percentage decrease.
- Adding or removing tax only? Use the sales tax calculator.
- Running a business and setting prices? The markup calculator shows what a discount does to your margin.
Discount Calculator FAQs
How do I calculate a percentage off?
Multiply the price by the percentage as a decimal to find the saving, then subtract it. 20% off $45 is 45 × 0.20 = $9 off, so you pay $36. Or multiply by 0.80 in one step.
Is 20% off then 20% off the same as 40% off?
No. It is 36% off. You pay 80% of 80%, which is 64% of the original price.
Is sales tax charged before or after a discount?
In most US states, sales tax is worked out on the price after a store discount. Enter the tax rate in the optional box to see the final total.
How do I find what percentage off an item is?
Divide the saving by the original price and multiply by 100. A $120 item reduced to $90 has a $30 saving: 30 ÷ 120 × 100 = 25% off.
For more shopping sums like these, see our everyday math examples.
How we checked this page: every example was worked by hand and matches the calculator, including the stacked discount and the rounded $249.99 example.