Discount calculator with double (stacked) discounts and sales tax
Enter a price and a discount, or the before and after prices, and see what you pay and what you save. Add your sales tax rate to see the total at checkout.
The short answer
Price after discount = original price × (1 − discount ÷ 100), so 25% off $80 is $60. The discount between two prices is (original − sale) ÷ original × 100. An extra discount applies to the already reduced price, which is why 50% off plus an extra 20% off is a 60% discount, not 70%.
How it is calculated
Sale price = price × (1 − discount ÷ 100)
Discount % = (original − sale) ÷ original × 100
Two stacked discounts: real discount = 1 − (1 − first) × (1 − second)
With sales tax: sale price × (1 + your tax rate ÷ 100)
Worked example
A jacket is $120.00, marked 30% off, with an extra 20% off at checkout. Sales tax is added at the register, here an example rate of 8.25%.
- After the first discount: $120.00 × 0.70 = $84.00
- After the extra discount: $84.00 × 0.80 = $67.20
- The real discount is 44%, not 50%. You save $52.80
- Sales tax at 8.25% on the reduced price: $67.20 × 0.0825 = $5.54
You pay $72.74 including sales tax.
Quick reference table
| Discount | $20 item | $50 item | $100 item | $250 item | $100 + 8.25% tax |
|---|---|---|---|---|---|
| 10% | $18.00 | $45.00 | $90.00 | $225.00 | $97.43 |
| 15% | $17.00 | $42.50 | $85.00 | $212.50 | $92.01 |
| 20% | $16.00 | $40.00 | $80.00 | $200.00 | $86.60 |
| 25% | $15.00 | $37.50 | $75.00 | $187.50 | $81.19 |
| 30% | $14.00 | $35.00 | $70.00 | $175.00 | $75.78 |
| 40% | $12.00 | $30.00 | $60.00 | $150.00 | $64.95 |
| 50% | $10.00 | $25.00 | $50.00 | $125.00 | $54.13 |
| 70% | $6.00 | $15.00 | $30.00 | $75.00 | $32.48 |
Special cases and common mistakes
- Stacked discounts do not add up. 50% off plus an extra 20% off is 60% off, and 30% + 20% is 44%. The order of the two discounts does not change the result.
- The calculator adds tax after the discount. Sales tax rates differ by state, city and province, so type the rate from your receipt or your area. Leave the tax box unchecked if the price you see already includes tax.
- Work backward from a sale price. Original = sale price ÷ (1 − discount). A $60.00 item at 25% off was originally $80.00.
Frequently asked questions
How do I calculate percent off?
Multiply the price by the discount and divide by 100 to get the amount you save, then subtract it. 15% off $40 saves you $6, so you pay $34.
How do I find the discount percentage between two prices?
Subtract the sale price from the original, divide by the original and multiply by 100. From $250 down to $175: 75 ÷ 250 × 100 = 30%.
Is 50% off plus 20% off the same as 70% off?
No. It is 60% off. A $100 item becomes $50 after the first discount and $40 after the second.
How much is 30% off $80?
$56.00. You save $24.00.
Does the calculator include sales tax?
Only if you check the box and enter your rate. It then adds the tax to the discounted price, so you see the total you would pay at checkout.