The short answer
How do stacked Black Friday discounts work?
Discounts multiply, they do not add. 30% off plus an extra 10% off is 0.70 × 0.90 = 0.63 of the price, a real discount of 37%, not 40%. On a $200 item you pay $126 before tax. Sales tax is then charged on the discounted price, so with 7% tax the total is $134.82.
Black Friday 2026 is Friday, November 27, the day after Thanksgiving (November 26). Cyber Monday is November 30.
Stacked discount table
| Sale | + extra 10% | + extra 15% | + extra 20% |
|---|---|---|---|
| 20% off | 28% off | 32% off | 36% off |
| 25% off | 32.5% off | 36.25% off | 40% off |
| 30% off | 37% off | 40.5% off | 44% off |
| 40% off | 46% off | 49% off | 52% off |
| 50% off | 55% off | 57.5% off | 60% off |
Formula: total discount = 1 − (1 − first) × (1 − second). A fixed-dollar coupon is worth more on a cheap item: $20 off a $50 item is 40%, but only 10% on a $200 item.
Is it really a deal? A checklist
- Check the "was" price. Some retailers raise the reference price before a sale. Price-history tools and the store's own price over the past few weeks show whether the discount is real.
- Compare the final total, not the percentage. Shipping, tax and membership requirements can erase a headline saving.
- Compare per unit. Bigger packs and bundles are not always cheaper; use the unit price calculator.
- Know the return and price-adjustment rules. Some stores refund the difference if the price drops again after you buy.
- Think about financing. Splitting a purchase with buy now, pay later is only free if every payment is on time.
- Set a budget first. A 40% discount on something you did not plan to buy is still spending.
Worked examples
TV
$899 TV, 25% off, $50 coupon, 8% tax: 899 × 0.75 = $674.25, − $50 = $624.25, + tax = $674.19. Real saving 30.6%.
Clothing
$80 jacket, 40% off, extra 20% at checkout, $6 shipping, no tax: 80 × 0.6 × 0.8 = $38.40 + $6 = $44.40.
Small item with a coupon
$35 item, $15 off a $35 purchase: you pay $20, a 43% discount; one item at $34.99 would not qualify.
Frequently asked questions
How do I calculate two discounts together?
Multiply the remaining shares of the price. 30% off then 10% off leaves 0.7 × 0.9 = 63% of the price, which is 37% off in total.
Is sales tax charged before or after a discount?
Usually after: sales tax is charged on the price you actually pay. Manufacturer coupons are treated differently in some US states.
When is Black Friday 2026?
Friday, November 27, 2026. Thanksgiving is Thursday, November 26, and Cyber Monday is November 30.
Is a percentage coupon or a dollar coupon better?
It depends on the price. A $20 coupon beats 10% off on items under $200; above $200, 10% off saves more.
How can I tell if a Black Friday deal is real?
Compare against the price over the previous weeks, not the store's list price, and compare the final total including shipping and tax.
Does the order of discounts matter?
For two percentage discounts, no: 30% then 10% gives the same result as 10% then 30%. A dollar coupon applied before a percentage discount saves less than one applied after.