Double Discount Calculator

Apply two successive discounts to any price and see the final price, total savings, and combined discount percentage. Add optional sales tax to get the complete total.

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Successive Discounts

Apply two discounts one after the other and see the true combined discount. Learn why 20% + 10% is not the same as 30% off.

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Step-by-Step Breakdown

See exactly how each discount is applied with a detailed breakdown showing prices at every step, plus optional sales tax.

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Frequently Asked Questions

How do you calculate a double discount?
To calculate a double discount, apply the first discount to the original price, then apply the second discount to the already-reduced price. For example, with a $100 item at 20% off then 10% off: $100 x 0.80 = $80 after the first discount, then $80 x 0.90 = $72 after the second. The final price is $72, and the combined discount is 28%.
Why is 20% + 10% not the same as 30% off?
When discounts are applied successively, the second discount is calculated on the reduced price, not the original price. With a $100 item, 30% off gives you $70. But 20% off then 10% off gives you $72, because the 10% applies to $80 (saving $8) instead of $100 (which would save $10). The difference of $2 is the "stacking penalty" shown in this calculator.
Does the order of discounts matter?
No, the order of percentage discounts does not change the final price. Applying 20% first then 10% gives the same result as applying 10% first then 20%. This is because multiplication is commutative: 0.80 x 0.90 = 0.90 x 0.80 = 0.72. You pay 72% of the original price either way.
What is the combined discount formula?
The combined discount formula for two successive discounts (d1 and d2) is: Combined = d1 + d2 - (d1 x d2 / 100). For 20% and 10%: 20 + 10 - (20 x 10 / 100) = 30 - 2 = 28%. This formula works for any two percentage discounts and always gives a result less than the simple sum of the two discounts.
When would I use a double discount calculator?
A double discount calculator is useful when stores offer stacked promotions, such as "20% off sale + extra 10% with coupon." It helps during Black Friday deals, employee discounts on top of sale prices, clearance markdowns with additional coupons, or loyalty member discounts combined with promotional offers. It shows you the true savings compared to what the percentages might suggest.