Double (Stacked) Discount Calculator
From an original price and two sequential discounts, compute the final price, total saved and the equivalent single discount rate.
Input Data
Results
At a glance:Sequential discount: after first = price x (1 - d1); final = x (1 - d2). Total saved = original - final; equivalent discount = (1 - final/original) x 100%. Because the second discount is on the reduced price, the equivalent is ALWAYS less than d1 + d2. Example: 100, 20% then 10% → final 72, saved 28, equivalent 28% (not 30%). Order doesn't matter (× commutes). WARNING: Whether discounts stack and on what base follows store terms — some exclude already-discounted items. Education, not advice.
Formula
After first = price × (1 − d1).
Final = after first × (1 − d2).
Equivalent single discount = (1 − final / original) × 100% (always < d1 + d2).
$$$P_1 = Price\\times(1-d_1)$$$$$$Final = P_1\\times(1-d_2)$$$$$$d_{eff}=\\left(1-\\dfrac{Final}{Price}\\right)\\times100\\%$$$How to Use
- Enter the original price and two discount percentages.
- View the final price, amount saved and equivalent single discount.
FAQ
Why is the equivalent discount less than the two added?
Because the second discount applies to the ALREADY discounted price, not the original. With original 100, 20% then 10%: after first 80, second takes 10% of 80 = only 8 off, total 28 off → equivalent 28%, not 30%. The second percentage acts on a smaller base, so it contributes less. Always compute sequentially, never just add.
Does the order of the two discounts matter?
No — multiplication commutes. 20% then 10% and 10% then 20% both give final = original x 0.8 x 0.9 = 0.72. The order does not change the result, though shops may sequence them to create a psychological illusion. The final price is identical either way.
Is two 50% off the same as 100% off (free)?
No — a common and serious misconception. 500, 50% then 50% → after first 250, then 50% of 250 = 125; final 125, equivalent 75% off. You still pay 125, never free. Because the second 50% is on the already-halved price. And as long as each discount is below 100%, the price approaches (never reaches) zero no matter how many times discounted.
Does the order really not matter, and is 50% off twice = free?
Order: genuinely does not matter for the final price, because both discounts are multipliers on the price and multiplication commutes (0.8×0.9 = 0.9×0.8). Shops may sequence them for a psychological 'first big cut' effect, but the math is identical. '50% off twice = free' is FALSE — it is 75% off, you pay 25%. Why people confuse it: they mentally add 50%+50%=100%, forgetting the second 50% is on the halved price (only 125 off a 500 base). Remember the equivalent is always less than the sum, and as long as each discount < 100%, price never reaches zero or negative.
What should I watch when an online store shows stacked discounts?
Three points. (1) Confirm whether they truly stack — some promos exclude already-discounted items, or 'second discount' applies only to part (e.g. clearance). Read the terms; our tool assumes standard sequential stacking. (2) Watch the base — is the second discount on the post-first price or on the original (rare but possible; if on original, the two do add)? The tool uses the standard 'on reduced price' convention. (3) Beware urgency/illusion — a 'extra 10% off' sounds like 10% more saving but only 10% of the reduced price. Compute the equivalent discount with this tool to see the real cut, then compare with the usual price to decide. Don't let 'double discount' framing rush you into overspending.
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References
Content review: Calculatorism Finance Team. Results are for reference only; please refer to the relevant authorities for the official figures.