The math in three easy steps
Say you find a $120 jacket marked 50% off, and the store adds “extra 20% off sale items” for Black Friday (Friday, November 27, 2026).
- First discount: 50% off $120 leaves $60.00.
- Extra discount: 20% off the new price, $60, is $12. You pay $48.00.
- Sales tax: at California’s average combined rate of 9.03%, tax is $4.33. Your total is $52.33.
The full price with tax would have been $130.84, so you save $78.51. The shortcut: multiply what you keep. 50% off keeps 0.50, 20% off keeps 0.80, and 0.50 × 0.80 = 0.40 — you pay 40% of the price, which means 60% off.
Common stacked discounts
The second discount always applies to the already-reduced price, so stacked deals are worth a bit less than adding the numbers. Here is what common combinations really mean, and the price of a $100 item before tax:
| Deal | Looks like | Really is | $100 item costs |
|---|---|---|---|
| 20% + extra 10% | 30% | 28.0% | $72.00 |
| 30% + extra 20% | 50% | 44.0% | $56.00 |
| 40% + extra 20% | 60% | 52.0% | $48.00 |
| 50% + extra 20% | 70% | 60.0% | $40.00 |
| 50% + extra 30% | 80% | 65.0% | $35.00 |
| 60% + extra 20% | 80% | 68.0% | $32.00 |
| 70% + extra 10% | 80% | 73.0% | $27.00 |
Good news: the order of two percentage discounts never matters. 50% then 20% is the same as 20% then 50%. Only a fixed dollar coupon changes with order (see our coupon guide).
A quick way to do it in your head
Standing in the aisle without a calculator? Turn each discount into “what I keep”: 50% off → keep half, 20% off → keep 8 tenths. Halve the price first ($120 → $60), then take off one fifth ($60 → $48). For 30% + 10%, take off 30% and then 10% of what is left. It only takes a few seconds and it stops the “70% off!” feeling from steering the decision.
A few friendly tips for Black Friday
- Check the “was” price. A discount is only as good as the starting price. If you can, compare with what the item sold for in October.
- Read the fine print on “extra % off”. It often applies only to items already on sale, or only at checkout with a code.
- Remember the tax. In most states, sales tax is added at the register on the discounted price. The calculator above lets you pick your state, or type your exact local rate.
- Keep the receipt. Many stores have special holiday return windows, and some offer a price adjustment if the price drops again.
FAQ
Is 50% off plus an extra 20% off the same as 70% off?
No. The extra 20% comes off the already-halved price, so the total discount is 60%. A $120 item costs $48.00 before tax, not $36.
How much is a $120 item at 50% + 20% off with California sales tax?
$48.00 before tax. With California’s average combined rate of 9.03%, tax is $4.33 and the total is $52.33.
Does it matter which discount is applied first?
Not for two percentages: 50% then 20% and 20% then 50% both give 60% off. Order only matters for a fixed dollar coupon.
Sources (checked 5 November 2026): Tax Foundation, “State and Local Sales Tax Rates, Midyear 2026” (rates as of July 1, 2026; Tax Foundation reports no statewide rate changes between January and July 2026), cross-checked against sales.tax midyear 2026 summary. Thanksgiving is the fourth Thursday of November (5 U.S.C. § 6103).