Stacked discounts multiply
The rule is one line: each discount applies to what is left, not to the original price.
| Stack | Effective | | --- | --- | | 20% + 10% | 28% | | 30% + 20% | 44% | | 50% + 50% | 75% | | 25% + 25% + 25% | 57.8% |
Two 50% discounts do not make something free. They make it a quarter of the price.
Reading a "70% off" claim
Big advertised percentages are usually against a list price. Enter the original and the price you would actually pay: the effective discount is what you got, and it is frequently well under the number on the sign.
When the difference is worth money
On a single small purchase, four percentage points is noise. On a procurement contract, a wholesale order, or a discount policy applied across thousands of transactions, treating stacked discounts as additive systematically overstates what you are giving away — and that error compounds every time it is applied.
Questions
Why is 20% plus 10% not 30%?+
Because the second discount applies to the already-reduced price. 20% off 1,000 is 800; 10% off 800 is 720. You paid 720 rather than 700, so the effective discount is 28%. The calculator shows both so the gap is visible.
Does the order of two discounts matter?+
No — multiplication commutes, so 20% then 10% gives the same result as 10% then 20%. It matters for tax and fees, which are often applied at a specific point in the sequence, but not for two straight percentage discounts.
How do I check an advertised discount?+
Enter the original price and the final price you were actually charged; the effective discount tells you what you really got. Advertised percentages are often applied to a list price nobody pays.
What about VAT?+
Discounts are normally applied before tax, then tax is calculated on the reduced amount. Use the [VAT calculator](/t/vat-calculator) on the final price for that step.