Stacked Discount Calculator
Last updated: November 14, 2026
Direct answer. Sale price = Original × (1 − D1 ÷ 100) × (1 − D2 ÷ 100) × …. A $100 item with 20% off, then 10% off, is $72, which is 28% off, not 30%. At an 8% tax on the sale price, tax is $5.76 and the total is $77.76.
U.S. checkout pages often let a percentage coupon stack after a sale markdown. Those percents are not added together. Each discount is applied to the price that remains. This calculator runs the discounts in the order you enter them and can then add a sales tax you supply.
Stacked Discount Calculator
Apply coupon or sale discounts one after another, then optionally add sales tax on the sale price. Two discounts are not added together.
Result
Key takeaways
- Stacked percent-off coupons multiply remaining fractions; they are not added.
- 20% then 10% off $100 leaves $72, a 28% combined discount.
- Optional sales tax, if entered, is applied to the sale price after all discounts.
- The order you enter the percents matches the order they are applied.
How to use this calculator
- Enter the original price in dollars.
- Add each percent-off coupon or markdown in the order it will be applied at checkout.
- Optionally enter a sales tax rate as a percent. Leave it blank to stop at the pre-tax sale price.
The formula
Each discount leaves a remaining fraction of 1 − D ÷ 100. Tax, if you include it, is a percent of the discounted sale price. Units are dollars for prices and percent for discounts and tax.
Worked examples
| Step | Rate | Price after the step | Notes |
|---|---|---|---|
| Start | $100.00 | Original price | |
| First coupon | 20% off | $80.00 | 100 × 0.80 |
| Second coupon | 10% off | $72.00 | 80 × 0.90 |
| Sales tax | 8% | $77.76 total | Tax $5.76 |
After 20% off the price is 80. After 10% off, 80 × 0.90 = 72. The amount saved is 28, or 28% off.
Tax is 72 × 0.08 = 5.76. The total with tax is 77.76.
When this is useful in the United States
A holiday checkout that lets you add a sitewide 20% code on top of an already marked-down item is the usual U.S. case for this math.
Gift-card or store-credit dollars are not percent coupons; do not enter them as a percent row. Subtract those after you have a sale price, or leave them out of this tool.
If a coupon is limited to a subset of a basket, run this calculator only on the eligible merchandise subtotal.
Common mistakes
- Adding 20 and 10 and taking 30% off. That would leave 70, not 72.
- Applying tax to the original price instead of the discounted sale price, unless a specific local rule says otherwise. This tool taxes the sale price.
- Entering a dollar-off coupon in the percent field.
Retailers sometimes advertise “up to 20% plus an extra 10% off.” Read the fine print: the second discount may apply only after the first, may exclude some SKUs, or may be a member price rather than a coupon. This calculator assumes every row is a percent of the remaining merchandise price, then an optional tax on that result. It does not model shipping, bottle deposits, or non-percent promotions. A “save 30%” headline that is really two stacked discounts will not match a single 30% markdown, and a receipt will usually show the $72 sale price rather than a 30% line. If you are writing ad copy, show the final price or the true combined percent off, which this calculator reports as the equivalent percent. Dollar-off codes, free-shipping thresholds, and buy-one-get-one deals need a different breakdown: apply the percent rows first only when the merchant does, then subtract dollars from that result by hand. Keep the original price, the sale price, and the tax in dollars, and the discounts and tax rate in percent, so the working remains easy to check. If a coupon has a minimum purchase or a category limit, apply this math only to the eligible portion of the basket. Combining an ineligible code here will overstate the discount. The equivalent percent off is a useful way to describe the stack in one number after the fact.
Frequently asked questions
Why is 20% then 10% not 30% off?
The second 10% applies to the already reduced price. On $100, that is 10% of $80, or $8, for $28 off in total (28%), not $30 off.
Does the order of coupons change the result?
For two pure percentage discounts, the combined remaining fraction is the product of the two factors, so the final pre-tax price is the same either way. The intermediate prices differ. Dollar-off coupons, which this percent tool does not model, can depend on order.
Is tax included automatically?
No. Enter a rate only if you want tax on the sale price. Confirm the rate from an official or merchant source; this page does not ship state rate presets.
Where can I read more about stacked discounts?
See the site guide on how successive discounts stack.