How do stacked percentage discounts work?

Sequential stacking applies each percent off the remaining price, so 20% then 10% is not 30% off — it is 28% off the original. Applying every percent to the original price instead is rarer and usually written that way on the receipt.

Do dollar coupons apply before or after percent off?

Most stores apply dollar-off coupons after sale and percentage discounts, then add tax. This calculator follows that order by default.

Is Black Friday tax calculated on the discounted price?

Sales tax is almost always charged on the price after discounts, not the sticker price. Enter your local tax rate as a percent.

Black Friday Discount Stack Calculator

Enter the sticker price, then stack up to three percentage discounts and a dollar coupon. The calculator shows each step, the true total savings, and the price after tax — so you can tell a real deal from a fake 70% off that is really 28%.

Original / sticker price ($)

How % discounts stack

Discount 1 (%)

Discount 2 (%)

Discount 3 (%)

Dollar coupon / gift card ($)

Sales tax (%)

Quantity

How the math works

sequential: price₁ = price₀ × (1 − d₁/100); price₂ = price₁ × (1 − d₂/100); … then − dollar coupon; then × (1 + tax/100)
original-base: take-off = price₀ × (d₁+d₂+d₃)/100; remaining = price₀ − take-off; then − coupon; then tax

Black Friday ads love to stack “extra 20% off already-reduced items.” That is almost never the same as adding the percents. A 30% sale followed by an extra 10% off is 0.70 × 0.90 = 0.63 of the sticker — a 37% total cut, not 40%. This calculator uses that sequential rule by default because it matches how registers ring up stacked promotions.

Dollar coupons and gift cards usually land after percentage discounts. Tax is then applied to the discounted subtotal (except in a few jurisdictions that tax the original price — check your receipt). Quantity multiplies the sticker price first, then the whole stack runs once on the cart total.

Worked example

A $199.99 TV with 30% off, then an extra 10% off, a $15 coupon and 8.25% tax:

After 30%: $139.99
After extra 10%: $125.99
After $15 coupon: $110.99
Tax 8.25%: about $9.16 → pay about $120.15
True savings vs sticker: about $89.00 before tax (≈ 44.5% off), not “40% + coupon on the full price.”

FAQ

Why isn’t 20% + 10% equal to 30%?: Because the second discount is taken from what is left. 20% then 10% leaves 72% of the original (28% off). Only “each percent off the original” mode adds them, and few stores actually do that.
Where do BOGO deals fit?: Treat “buy one get one 50% off” as roughly a 25% cart discount on two equal items, or enter the discounted item’s price as a dollar coupon. Exact BOGO rules vary by store.
Should I include shipping?: Add shipping as a negative dollar coupon (enter 0 here) and compare free-shipping thresholds separately — shipping is rarely discounted the same way as the merchandise.
Does this work for Cyber Monday too?: Yes. The same stacking math applies to Cyber Monday, Amazon Prime Day, and any “extra % off sale price” promo.

This tool is for shopping math only. Store policies, excluded brands, and local tax rules can change the final charge — always confirm on the checkout page.

Black Friday Discount Stack Calculator

How the math works

Worked example

FAQ

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