Discount Calculator

How this discount calculator works

Enter the original price and a discount percentage to get the final price and the dollar amount you save. There's also an optional second discount field for stacked promotions — a coupon on top of a sale price, or a loyalty discount applied after a seasonal markdown. The second discount is calculated on the already-reduced price left over from the first, exactly how stacked discounts actually work at checkout, and the calculator reports the true "effective discount" percentage against the original price so you know your real total saving, not just the two percentages you started with.

The exact formula

A single discount is final price = original price × (1 − discount% ÷ 100), and saved = original price − final price. Stacking a second discount applies the same formula again to the output of the first: price after first discount = original price × (1 − d1 ÷ 100), then final price = price after first discount × (1 − d2 ÷ 100). The effective discount you actually received is effective% = (original price − final price) ÷ original price × 100. Because each successive discount is applied to a shrinking base, effective% is always less than d1 + d2 whenever both discounts are greater than zero.

A worked example

Take a $100 item with a 20% storewide sale discount, and you also have a 10% coupon that stacks on top. First discount: $100 × (1 − 0.20) = $80.00. Second discount, applied to that $80, not the original $100: $80.00 × (1 − 0.10) = $72.00. You paid $72.00 for a $100 item, saving $28.00 — an effective discount of $28.00 ÷ $100 × 100 = 28%, not the 30% you'd get by naively adding 20% and 10% together. That two-percentage-point gap is the compounding effect of applying the second discount to a smaller base, and it grows larger as either discount percentage grows.

When this calculator matters

Retail and e-commerce shoppers hit stacked discounts constantly — a clearance markdown plus an app-exclusive coupon, a membership discount on top of a flash sale, or a "extra X% off already-reduced items" promotion. Knowing the true effective discount lets you compare that deal honestly against a competing store's single flat discount, rather than being misled by two impressive-sounding percentages that don't actually add to what they imply. Sellers and marketers use the same math in reverse when structuring a promotion — deciding how to combine a sitewide sale with a coupon code so the total effective discount lands at a specific target without giving away more margin than intended. Anyone reconciling a receipt against an expected discount can also use this to check the math actually matches what was advertised.

Common mistakes to avoid

The single biggest mistake is adding stacked discount percentages together — 20% + 10% is not 30% off, it's 28% off, and the gap only grows with bigger numbers (30% + 30% is 51% off, not 60%). A second mistake is applying both discounts to the original price independently and adding the two dollar amounts, which produces the same wrong 30%-style answer through a different route. A third, subtler mistake is assuming discount order matters — it doesn't; 20% then 10% and 10% then 20% both land on exactly $72.00, because multiplication is commutative, so retailers advertising "extra 10% off" after a sale aren't hiding anything by the order they list the discounts. Finally, remember that a discount and a markup aren't mirror images of the same operation: to undo a 20% discount and get back to the original price, you'd need roughly a 25% markup on the discounted price, not a 20% one — a distinction worth checking with the Markup Calculator if you're working in that direction.

Working backwards: finding the original price from a sale price

Sometimes you have the opposite problem — you see a sale price and the advertised discount percentage, and you want the original price rather than the other way around. The formula rearranges cleanly: original price = sale price ÷ (1 − discount% ÷ 100). If an item is on sale for $80 at "20% off," the original price was $80 ÷ 0.80 = $100. This comes up when comparing a "was/now" pricing claim across stores, or when a receipt only shows the final discounted price and you need to reconstruct the pre-discount value for expense reporting or price-history tracking. Watch for the same trap as before if two discounts were stacked to reach that sale price — reversing a single "effective" percentage assumes it was one discount, not two compounded ones, so if you know both original discounts were stacked, reverse them in the opposite order they were applied, one at a time.

Discounts, coupons and rebates — not quite the same thing

The math here applies to any percentage-off reduction taken at the point of sale, but it's worth distinguishing a few related terms that get used loosely. A discount or coupon reduces the price you pay at checkout, exactly as modeled here. A rebate, by contrast, is typically a partial refund paid back to you after you've already paid the full price — you finance the discounted amount temporarily and get it back later, which matters for cash-flow timing even if the final net cost is mathematically the same. A price match or loyalty credit may also stack with a percentage discount in ways specific to the retailer's own rules, sometimes applied before the percentage discount and sometimes after — always check whether a flat-dollar credit is applied before or after a percentage discount, since (unlike two percentage discounts) the order does change the final result when a flat-dollar amount is involved.