Discount Calculator
Sale price and savings from any percent off — with stacked-discount math done right — or reverse it to find the true percent off.
How to use this tool
- Enter the original price and the percent off — add a second discount if the store stacks one (e.g., 'extra 20% off clearance').
- Or flip to reverse mode: enter the original and sale price to see the true percent off.
How it works
The stacking trap is why this calculator shows its sequence: '20% off plus an extra 10% off' is 28% total, not 30%, because the second discount applies to the already-reduced price (0.8 × 0.9 = 0.72 of original). Retailers know shoppers add the percentages; the calculator multiplies them, which is what the register will actually do.
Sale price = price × (1 − discount). Stacked discounts apply in sequence, not by adding: 30% off then an extra 20% off is price × 0.70 × 0.80 = 44% total off, not 50% — which is why 'extra' discounts feel smaller than expected. Informational only — final pricing, coupon stacking rules, and tax treatment are set by the retailer.
Content last reviewed: July 2026.
Frequently asked questions
Why isn't 20% + 10% the same as 30% off?
Because the second discount applies to the reduced price, not the original. $100 at 20% off is $80; 10% off that is $72 — a 28% total discount. Stacked percentages always total less than their sum.
Do stacked discounts add together?
No — they multiply. 30% off plus an extra 20% off gives 44% total, because the second discount applies to the already-reduced price. The calculator shows the effective total discount.
How do I figure out what percent off a sale really is?
Use reverse mode: (original − sale) ÷ original × 100. A $80 item marked to $60 is 25% off.
Is tax charged on the discounted price?
In general, yes — US sales tax typically applies to the price actually paid after store discounts (manufacturer coupons vary by state). Pair with our Sales Tax Calculator for the final total.