Percent Calculator

Black Friday Discount Calculator

Stacked discounts multiply, they do not add: Final = Price × (1 − p1/100) × (1 − p2/100). Example: $100 with 30% then 10% is $63 (37% effective), not $60. Real off-tag % = (Was − Sale) ÷ Was × 100.

Last updated 2026-11-04 · Reviewed by Oguzhan Aydin

Calculate

Mode
Original price
First discount %
Extra discount %

Result

$63.00

$100.00 × (1 − 30/100) × (1 − 10/100) = $63.00 (effective 37.00%, not 40%)

% of a numberIncreaseDiscount
Original$100.00
After stack$63.00
Savings$37.00
Effective % off37.00%
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Stacked deals, real off-tag %, and cart savings

Formula

Stacked: Final = Price × Π(1 − pᵢ/100). Real % = (Was − Sale) ÷ Was × 100. Cart savings = Σ(priceᵢ − finalᵢ).

How to calculate a Black Friday discount

  1. Pick stacked discounts, was-vs-sale check, or a multi-item cart.
  2. Enter prices and percent offs (second discount applies to the reduced price).
  3. Read the final price, effective percent, or total cart savings.

Formula:

Final = Price × (1 − p1/100) × (1 − p2/100)

Reference table

DealWrong (add)Correct (stack)
$100 · 20% + 10%$70$72
$100 · 30% + 10%$60$63
$100 · 50% + 20%$30$40

Worked examples

$100 with 30% then 10%

Result: $63 final (37% effective, not 40%)

Was $200, sale $140

Result: 30% real discount

Cart: $80 @30% + $50 @20%

Result: Save $34; pay $96

Frequently Asked Questions

How do stacked Black Friday discounts work?

Apply each percent in order to the remaining price. 30% then 10% on $100 is $100 × 0.7 × 0.9 = $63. Adding 30 + 10 = 40% would wrongly give $60.

How do I know if a “was” price is a real discount?

Divide (was − sale) by was and multiply by 100. If the sale is higher than was, it is not a discount.

Can I total savings for a whole cart?

Yes. Enter up to five item prices and their percent offs. The calculator sums the savings line by line.

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