Instantly calculate sale price, dollar savings, and percentage discount. Works in all directions: enter original price + discount % to get sale price, or enter original + sale price to find the discount percentage. Also includes tax calculation and bulk discount comparison. Free, instant, no sign-up.
Sale price, savings & discount percentage
Understanding discounts is a core everyday financial skill. A 20% discount on a $100 item gives a sale price of $80 and a saving of $20. A 30% discount on a $250 item: $250 × 0.70 = $175 sale price, saving $75. The formula: Sale Price = Original Price × (1 − Discount%/100). To find the discount percentage when you know both prices: Discount% = (Original − Sale) / Original × 100. For "X% off" stacked on a sale price that's already discounted, the discounts are NOT additive — a 20% off plus an additional 10% off yields: $100 × 0.80 × 0.90 = $72 (28% total off, not 30%).
In retail, common discount psychology includes "was $99, now $79" (showing original price inflates perceived value), "buy 2 get 1 free" (equivalent to 33% off per item), and "up to 70% off" (usually only one item in the sale is 70% off). When evaluating deals, always calculate the per-unit price and compare against alternative retailers before purchasing. This calculator handles all these scenarios including bulk quantity pricing and sales tax to give you the true all-in cost before you buy.
Two sequential discounts are NOT additive. 20% off + 10% off = 28% total (not 30%). Formula: Final = Original × (1−d1) × (1−d2). Example: $200 × 0.80 × 0.90 = $144. The order of discounts doesn't matter — the result is the same. This calculator handles the correct multiplicative math automatically.
Black Friday (Nov 28): average 20–30% off electronics, 30–50% off clothing. Cyber Monday: best for tech deals. Amazon Prime Day (July): members-only deals, avg 20–40% off. End-of-season sales: 40–70% off clothing in Jan and July. Memorial Day/Labor Day: best for appliances, mattresses, furniture — 20–40% off.
At most retailers, coupons apply to the pre-sale price. Check your store's policy: "coupon applies to original price before discount" vs "coupon applies to sale price." Target Circle and Walmart+ members can stack savings. Store credit cards often add 5% back. A 25% sale + 5% card cashback effectively = 28.75% off (not 30% — stacking is multiplicative).
Sales tax is calculated on the discounted price (after discount), not the original price — which is a common misconception. A $100 item at 20% off in a state with 8% tax: ($100 × 0.80) × 1.08 = $86.40. Average US state sales tax: 6.0%. Combined with local taxes, average effective rate is ~7.12%. Oregon, Montana, New Hampshire, Delaware, and Alaska have 0% state sales tax.
A single discount is trivial arithmetic; the interesting cases are the ones shoppers get wrong. Stacked discounts do not add — 20% off then a further 10% off is 28% off, not 30%, because the second reduction applies to the already-reduced price. Sales tax applied afterwards operates on the discounted amount, so the order of operations matters to the final total. And "50% off" against an inflated reference price is a smaller saving than it appears, which is why unit price is the honest comparison.
Sale price = Original × (1 − discount)Stacked: Final = Original × (1 − d₁) × (1 − d₂)Amount saved = Original − Sale pricewhere:
Assumptions: Assumes discounts apply to the whole price rather than to selected items, and that tax is calculated on the post-discount figure — which is the normal rule in US sales tax jurisdictions.
A $240 jacket is marked 30% off, with a coupon for a further 15% at the register, in a state with 7% sales tax.
Result$142.80 before tax, $152.80 paid — a 40.5% combined discount
The shortcut for stacking is 1 − (0.70 × 0.85) = 0.405. Adding the percentages would have promised $108 of saving against the real $97.20 — a $10.80 gap on one item.