Calculators & everyday math
Stacked Discounts: Why 20% Plus 10% Off Isn’t 30%
Discounts often stack: a sale price plus an “extra 10% off” coupon, or a member discount on top of a promotion. Stacked percentages don’t simply add up. This guide shows why, how to work out the real total discount, and how to compare stacked offers with single ones.
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How stacked discounts work
Each discount applies to the price left after the one before it. $100 with 20% off becomes $80; an extra 10% off $80 takes off $8, leaving $72. The total saving is $28, or 28% — not 30%.
The multiplier shortcut
Turn each discount into the share you pay and multiply: 20% and then 10% off is 0.8 × 0.9 = 0.72, so you pay 72% and save 28%. The order doesn’t matter — 10% and then 20% also gives 0.72.
| Discounts | You pay | Total discount |
|---|---|---|
| 20% + 10% | 72% | 28% |
| 30% + 20% | 56% | 44% |
| 50% + 20% | 40% | 60% |
| 25% + 25% | 56.25% | 43.75% |
| 40% + 10% + 5% | 51.3% | 48.7% |
Comparing offers
A single 30% discount beats 20% plus an extra 10% by 2% of the original price. On a $150 purchase that is $105 versus $108.
Percentages and fixed-amount coupons
When a percentage discount is combined with a fixed amount such as $10 off, the order does matter. On $100, 20% off and then $10 off gives $70, while $10 off and then 20% off gives $72. Check the store’s terms for which applies first.
Finding the total discount from what you paid
If you only know the original price and what you finally paid, the total discount is (original − paid) ÷ original × 100. Paying $72 for a $100 item is 28% off overall.
Stacked Discounts FAQ
- Is 20% off plus an extra 10% off the same as 30% off?
- No. It is 28% off, because the extra 10% comes off the already reduced price.
- Does the order of percentage discounts matter?
- No. Multiplying the shares you pay gives the same result in any order.
- Does the order matter with a fixed-amount coupon?
- Yes. Taking the fixed amount off first leaves a smaller price for the percentage to work on, so you save less.
- How do I work out stacked discounts with the Discount Calculator?
- Apply the first discount, then enter the sale price as the new original price and apply the second.
- What is 50% off plus an extra 20% off?
- 60% off in total: you pay 0.5 × 0.8 = 40% of the original price.
Related guides
- Calculate a Sale DiscountWork out a sale price and your savings, find the original price from a sale price, and find the discount percentage when a shop shows only two prices.
- Savings at Common DiscountsA quick reference of sale prices at 10%, 20%, 25%, and 50% off, mental shortcuts for each, and why a bigger percentage isn’t always the better deal.
Open the tool
Jump into Discount Calculator when you are ready to process your files.
