Coupon Stacking Calculator
Stacking two coupons does not simply add their percentages, and this calculator shows the real number. When two percentage discounts apply one after the other, the second is taken on the already-reduced price, so the combined saving is always a little less than the two rates added together. The tool starts from the original price, applies the first discount, then applies the second to what is left, and reports the final price and the total saving in dollars. A common surprise is that 20% then 10% is a 28% reduction, not 30%, because the 10% comes off the smaller amount. Enter your own price and two discount rates to check a stacked promotion, compare a single big coupon against two smaller ones, or settle the "is it really 30 percent off" question. The order of two percentage discounts does not change the final price, since multiplying the fractions is the same either way. Many retailers cap you at one offer per purchase, so confirm that stacking is allowed before relying on the result. Every figure here is computed deterministically from successive percentage discounts, shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step.
Stacked discounts multiply the remaining fractions: final = price x (1 - d1) x (1 - d2). On $100.00, a 20% then 10% discount gives a final price of $72.00, a total saving of $28.00 (a 28% reduction, not 30%).
Coupon stacking formula
Final price = price x (1 - d1) x (1 - d2)
price = original price ($)
d1 = first discount (as a decimal)
d2 = second discount (as a decimal)
Total saving = price - final price
Each discount leaves a remaining fraction of the price; multiplying those fractions gives the final price, and subtracting from the original gives the saving.
Worked example
An item priced at 100 dollars with a 20% coupon then a 10% coupon.
- After first discount: 100 x (1 - 0.20) = 80
- After second discount: 80 x (1 - 0.10) = 72
- Total saving = 100 - 72 = 28.00
- Final price = $72.00
The final price is 72.00 dollars, a saving of 28.00 dollars. These are the calculator's default inputs, so the result above matches the widget exactly.
Stacked discounts on 100 dollars
The combined reduction is always less than the sum of the two rates.
| Discounts | Final price | True reduction |
|---|---|---|
| 10% + 10% | $81.00 | 19.00% |
| 20% + 10% | $72.00 | 28.00% |
| 25% + 15% | $63.75 | 36.25% |
| 30% + 20% | $56.00 | 44.00% |
Pricing and measurement references: US National Institute of Standards and Technology (NIST).
Coupon stacking calculator: frequently asked questions
How do stacked discounts work?
When two percentage discounts apply one after the other, the second is taken on the already-reduced price, not the original. A 20% then 10% discount on 100 dollars leaves 80 after the first and 72 after the second, a final price of 72 dollars.
Is 20% plus 10% the same as 30% off?
No. Successive discounts of 20% and 10% give a 28% total reduction, not 30%, because the 10% is applied to the smaller post-discount amount. Stacked percentage discounts always save a little less than the two rates added together.
How do I find the combined discount?
Multiply the remaining fractions and subtract from one. Twenty percent off leaves 0.80, ten percent off leaves 0.90, and 0.80 times 0.90 is 0.72, so 28% is taken off in total. The order of the two discounts does not change the final price.
Does the order of discounts matter?
For two percentage discounts, no. Multiplication is commutative, so 20% then 10% gives the same final price as 10% then 20%. Order can matter only when a fixed-dollar coupon is mixed in, where the rules of the promotion decide the sequence.
Can I always stack coupons?
Not always. Many retailers limit you to one offer per purchase or exclude certain items, so check the terms before assuming two discounts combine. This calculator shows the result when stacking is allowed.
Official sources
- Pricing arithmetic and measurement references: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.