Sequential discounts are multiplied, not added. The fixed coupon is applied after percentage discounts and the result is floored at zero.
Calculation details
Planning estimate only. Platform fees, taxes, payment costs, and policies can change; verify current terms before pricing.
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What does this calculator estimate?
This percent off calculator applies the first discount to the original price, then applies the second discount to that reduced amount. It subtracts a coupon after both discounts and adds tax last, so the result reflects the order used at checkout. Enter finite values and a nonnegative original price.
- Successive discounts multiply: 20% then 10% off equals 28% total off, not 30%. (Source: BoringToolsKit calculation methodology)
- A $5 coupon on a $139 cart is about 3.6% effective savings, far less than it feels. (Source: BoringToolsKit calculation methodology)
- Sales tax applies to the final discounted price, not the original sticker. (Source: BoringToolsKit calculation methodology)
Why does stacking two 20% discounts not equal 40% off?
Stacked discounts apply sequentially: the second percentage acts on the already-reduced price, not the original. Two 20% discounts leave 0.8 x 0.8 = 64% of the price, an effective 36% off, not 40%. Retailers describe stacked offers in ways that encourage the simpler mental math; computing the effective total discount prevents that slip.
Is a dollar-off coupon better than a percentage coupon?
It depends on the price. A $10-off coupon beats 10% off once the item exceeds $100, and loses below it. Convert both to dollars on the actual price before comparing, and remember that percentage coupons scale up on expensive items while fixed coupons do not. This calculator applies the coupon after the percentage discount, matching the order most checkout systems use.
How this calculator works
Formula
After first discount = original price × (1 − first rate ÷ 100). After second discount = first result × (1 − second rate ÷ 100). Pre-tax final = max(0, second result − coupon). Tax = pre-tax final × tax rate ÷ 100.
Worked example
A $200 item discounted 20%, then 10%, with a $5 coupon becomes $139 before tax. At 8% tax, the checkout total is $150.12 and effective pre-tax savings are 30.5%.
Assumptions to verify
- Percentage discounts are applied sequentially rather than added together.
- The fixed coupon is applied after percentage discounts and cannot make the price negative.
- Tax is an editable estimate; taxable bases and local rules can differ.
Frequently asked questions
How do you calculate stacked discounts?
Apply the first percentage discount to the original price, then apply the second percentage to the reduced price. Do not add the percentages together.
Is a coupon applied before or after the discounts?
This calculator subtracts the coupon after discount 1 and discount 2 have been applied, then calculates tax on the resulting amount.
How do you calculate sale price with tax?
Apply both percentage discounts in sequence, subtract the coupon, then multiply the remaining amount by one plus the tax rate.
Cite this tool
BoringToolsKit. “Percent Off Calculator.” boringtoolskit.com/discount-percent-off-calculator/ (reviewed July 2026). Free to reference in articles, syllabi, and answer posts with a link.
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