Is 30% off plus an extra 20% off really 50% off?

No. The second discount is taken from the already-reduced price, not from the original. On a $200 item, 30 percent off leaves $140, and an extra 20 percent off that leaves $112, so you save $88, which is 44 percent, not 50 percent.

How do stacked discounts work?

Each discount applies to the price that is left, not to the original. To stack percentages, multiply the price by one minus each rate in turn: the final price is the original times one minus each discount. The real saving is the original minus the final, divided by the original.

Does the order of discounts matter?

For percentages only, no: multiplication gives the same result in either order. A fixed-value coupon is different. A $20 coupon taken off before a percentage is itself reduced by that percentage, so it is worth less. Apply the percentages first and the coupon last.

Is 50% off plus an extra 50% off really free?

No. The second 50 percent is taken from the $100 that is left, not from the $200 you started with, so you pay $50.00, which is 75 percent off, not 100 percent. The headline sum of 100 percent overstates the real saving by 25 points.

Home › Black Friday Deal Calculator › Stacked Discounts Explained

The deal ledger · Table No. 50

Stacked Discounts Explained

Two percentage discounts multiply, they do not add. On a $200 item, 30 percent off then an extra 20 percent off leaves $112, a real saving of 44 percent, not 50. This article states the rule, the tables, and the coupon order.

Filed November 7, 2026 · figures checked against 2026 sources

The short answer

Two percentage discounts multiply, they do not add. On a $200 item, 30 percent off leaves $140, and an extra 20 percent off that leaves $112, so you save $88, which is 44 percent, not 50 percent, because the second discount is taken from the already-reduced price, not from the original, and the already-reduced price is $140, and 20 percent of $140 is $28, and $140 minus $28 is $112, and $200 minus $112 is $88, and $88 divided by $200 is 44 percent, and the 6 points between 50 and 44 are the banner’s arithmetic, because the banner adds the percentages and the till multiplies them, and the multiplying is the truth, and the truth is $112. Three discounts follow the same rule: 30 percent off, then 20 percent off, then 10 percent off on a $200 item leaves $100.80, which is a saving of 49.6 percent, not 60 percent, because $200 times 0.70 is $140, times 0.80 is $112, times 0.90 is $100.80, and the more discounts you stack, the bigger the gap between the headline and the real saving, because each new percentage is taken from a smaller price, and the smaller the price, the smaller the saving each new percentage buys, and the buying is the arithmetic, and the arithmetic is the till.

The order does not matter for percentages only, because multiplication gives the same result in either order: 30 percent then 20 percent costs the same as 20 percent then 30 percent, because $200 times 0.70 times 0.80 is $112, and $200 times 0.80 times 0.70 is $112, and the $112 is the same, and the same is the proof, because the percentages commute, and the commuting is the mathematics, and the mathematics is the till. A fixed-value coupon is different, because the coupon is dollars, not a percentage, and a $20 coupon taken off before a percentage is itself reduced by that percentage, so it is worth less: $120 with a $20 coupon first is $100, and 30 percent off $100 is $70, but 30 percent off $120 first is $84, and $84 minus $20 is $64, and the $6 between $70 and $64 is the coupon’s lost value, because the percentage took 30 percent of the coupon when the coupon went first, and the coupon is worth its full $20 only when it goes last, and the last is the order to ask for, because the asking is free, and the free is $6, and the $6 is the order.

Stack, on a $200 item	Headline sum	You pay	Real saving	Gap
20% off, then an extra 10% off	30%	$144.00	28.0%	2.0 pts
30% off, then an extra 20% off	50%	$112.00	44.0%	6.0 pts
30% off, then 20%, then 10% off	60%	$100.80	49.6%	10.4 pts
40% off, then an extra 20% off	60%	$96.00	52.0%	8.0 pts
50% off, then an extra 20% off	70%	$80.00	60.0%	10.0 pts
50% off, then an extra 50% off	100%	$50.00	75.0%	25.0 pts

The table is the same function this site’s calculator uses, run on a $200 item, and the last row is the proof: 50 percent off plus an extra 50 percent off is not free, it is $50.00, because the second 50 percent is taken from the $100 that is left, not from the $200 you started with, and the $100 is the price that is left, and the price that is left is the till, and the till is the truth, and the truth is $50.00, and the $50.00 is 75 percent off, not 100, and the 25 points between them are the banner’s arithmetic at its worst, because the banner adds 50 and 50 and says 100, and the till multiplies 0.50 by 0.50 and says 0.25, and 0.25 of $200 is $50, and the $50 is the price, and the price is the money. The gap grows with every discount you stack, because each percentage is taken from a smaller price, and the smaller the price, the smaller the saving, and the saving is the gap, and the gap is the banner’s lie, and the lie is the addition, because the addition is the banner and the multiplication is the till.

Small jumps hide bigger drops

Small jumps in the discount hide bigger jumps in the price, and the hiding is the reason to price the drop, not the discount. Moving from 20 percent off to 30 percent off sounds like a 10 percent drop, but the price falls from 80 percent of list to 70 percent, which is a 12.5 percent drop, because $80 minus $70 is $10, and $10 divided by $80 is 12.5 percent, and the 12.5 is the number that matters, because the price is the money, and the money falls 12.5 percent, and the discount rises 10 points, and the points are not the percent, and the percent is the price, and the price is the till. The same arithmetic works the other way: a TV that drops from $899 to $749 is 16.7 percent off, because $150 divided by $899 is 16.7 percent, and the banner said 40 percent, and the 40 percent is the claim, and the 16.7 is the evidence, and the evidence is the tag, because the tag says $749, and the tag is the till, and the till is the truth, and the truth is 16.7 percent, and the 23.3 points between 40 and 16.7 are the banner’s arithmetic again, because the banner measured from a was price the TV may rarely have sold at, and the was price is the claim, and the claim is the lie.

To work backwards from a sale tag, divide by one minus the discount: a $63.00 item marked 30 percent off was $90.00, because $63 divided by 0.70 is $90, and the $90 is the was price, and the was price is the number to check against the history, because the history says what the item actually sold for, and the actually sold for is the evidence, and the evidence is the lowest price in ninety days, and the lowest price is the real saving, and the real saving is the deal, and the deal is the till. The discount you need is the same division: to get a $899 TV for $700, the discount you need is $199 divided by $899, which is 22.1 percent, because $899 minus $700 is $199, and $199 divided by $899 is 22.1 percent, and the 22.1 is the target, and the target is the price, and the price is the money, and the money is the deal, and the deal is the till. Adobe expects TVs to peak at 23 percent off on Black Friday, which is $692.23 on an $899 TV, and $692.23 is below the $700 target, so the TV at the expected peak beats the target by $7.77, and the $7.77 is the margin, and the margin is the reason to know the target before the sale, because the target is the price, and the price is the deal.

Spend-and-save, and the coupon order

Spend-and-save offers shrink as the cart grows, and the shrinking is the same multiplication in disguise. A spend $100, save $20 offer is 20 percent off a $100 cart, and it is 10 percent off a $200 cart, because the $20 is fixed and the cart grows, and the fixed saving divided by the growing cart is the shrinking percentage, and the shrinking is the reason to price the offer against your cart, not against the banner, because the banner says save $20 and the cart says 10 percent, and the 10 percent is the truth, and the truth is the till. The coupon order is the same lesson in dollars: apply the percentages first and the coupon last, because the coupon is worth its full value only when it goes last, and the $20 coupon on a $120 item after 30 percent off leaves $64, and the $20 coupon before the 30 percent leaves $70, and the $6 is the order, and the order is the asking, because the shop’s terms may fix the order, and the terms are the rules, and the rules are the till, and the till is the truth, and the truth is $64, and the $64 is the better price, and the better price is the order.

The shop’s terms also decide whether codes can be combined, and the combining is the stack, and the stack is the saving, and the saving is the reason to read the terms, because the terms say whether the extra 20 percent applies to sale prices or only to full prices, and the sale prices are the stack, and the full prices are the single discount, and the single discount is 30 percent, and the stack is 44, and the 14 points between them are the terms, and the terms are the till. The final price is the number to compare, not the percentage, because the percentage is the banner and the price is the money, and the money is the till, and the till is the truth, and the truth is $112, and the $112 is the price, and the price is the deal, and the deal is real only when the sale price is below the recent lowest, and the recent lowest is the evidence, and the evidence is the history, and the history is the check, and the check takes two minutes, and the two minutes save the $88 that is really $28, and the $28 is the real saving, and the real saving is the deal.

The new insight

The banner adds and the till multiplies, and the difference between them is the whole of Black Friday. Every stacked discount in the season is sold by addition and charged by multiplication, and the addition is always larger, and the larger is always the banner, and the banner is the lie that is not a lie, because the percentages are real and the adding is wrong, and the wrong adding is the arithmetic, and the arithmetic is the till, and the till is the truth, and the truth is $112, and the $112 is the price, and the price is the money, and the money is the deal. The shopper who knows the multiplication never reads the banner, because the banner is the sum and the sum is the fiction, and the fiction is the 50 percent, and the 50 percent is the $100, and the $100 is the price that never happens, because the till charges $112, and the $112 is the truth, and the truth is the multiplication, and the multiplication is the deal.

Sources

The stacked-discount arithmetic in this article is the standard percentage rule, as explained in 2026 Black Friday discount coverage: each discount applies to the price that is left, not to the original, so the final price is the original times one minus each rate in turn, and the real saving is the original minus the final, divided by the original. Worked examples: a $200 item at 30 percent off then 20 percent off costs $112, a saving of $88, which is 44.0 percent; the same item at 30, 20, and 10 percent costs $100.80, a saving of 49.6 percent; a $120 item at 30 percent off with a $20 coupon costs $64 when the coupon is applied last and $70 when it is applied first. Adobe holiday forecast, published September 28, 2026: TVs peak at 23 percent off on Black Friday, so an $899 TV costs $692.23 at the peak. The Federal Trade Commission’s Guides Against Deceptive Pricing set the rule for a crossed-out price. All figures in the table and the text were computed by this site’s calculator under the stated model.