Big sales love double offers: “Flat 50% + extra 20% at checkout”, “30% off plus 10% for card holders”. It is natural to add the numbers together, but stacked discounts never work that way. This article explains why, gives you a one-line formula and shows how to compare offers using our Discount Calculator.
How stacked discounts are applied
Each discount is applied to the price left after the previous one. With 50% + 20% on Rs 8,000:
- 50% off Rs 8,000 = Rs 4,000
- 20% off Rs 4,000 = Rs 3,200
You pay Rs 3,200. The total saving is Rs 4,800, which is 60%, not 70%.
The one-line formula
Total discount = 1 − (1 − d1) × (1 − d2) × …
For 50% and 20%: 1 − (0.5 × 0.8) = 1 − 0.4 = 0.6, which is 60%.
Common combinations
| Offer | Real total discount |
|---|---|
| 10% + 10% | 19% |
| 20% + 10% | 28% |
| 30% + 20% | 44% |
| 40% + 10% | 46% |
| 50% + 20% | 60% |
| 50% + 50% | 75% |
Does the order matter?
No. Applying 20% first and then 50% gives the same final price. Multiplication does not care about order, so a shop cannot make you pay more by changing the sequence of percentage discounts.
When fixed-amount discounts are mixed in
Order does matter when one discount is a fixed amount, such as “Rs 500 off” with a voucher. On a Rs 4,000 item with 25% off and a Rs 500 voucher:
- Voucher first: (4,000 − 500) × 0.75 = Rs 2,625
- Percentage first: 4,000 × 0.75 − 500 = Rs 2,500
Applying the percentage first saves more for you, which is why most shops apply the voucher at the end anyway.
Comparing two offers
Shop A: 35% off. Shop B: 20% + extra 20%. Shop B’s real discount is 1 − 0.8 × 0.8 = 36%, slightly better than Shop A, if the starting prices are the same. Always compare the final price in rupees; our Percentage Calculator can turn any two prices into a percentage difference.
Cashback is another layer
A bank card offering 10% cashback adds another stack, but cashback often has a cap. A 10% cashback capped at Rs 1,000 is worth less than 10% on bigger purchases. See discount vs cashback for a deeper comparison.
A note for sellers
If you run a shop, stacked offers can eat your margin faster than you expect. A 30% sale plus a 10% card discount is a 37% price cut, and if your margin is 35% you are now selling at a loss. Check your numbers with the Profit Margin Calculator before agreeing to extra discounts with banks or marketplaces.
Back to basics
If you need a refresher on single discounts, finding the percentage from two prices or working back to the original price, see how to calculate discount. And when sales tax is added after the discount, the VAT Calculator shows the final amount.
Frequently asked questions
How do you calculate two discounts together?
Apply the first discount, then apply the second discount to the new price. Or use 1 − (1 − d1) × (1 − d2).
Is 20% + 20% the same as 40% off?
No, it is 36% off.
Does the order of discounts matter?
Not for two percentage discounts; it can matter when a fixed-amount voucher is involved.