Discount Calculator
Original price, percent off, done. Add a second stacked discount ("extra 20% off clearance") and tax to see the real checkout total.
Stacked discounts don't add up — literally
"25% off, plus an extra 20% off" is not 45% off. The second discount applies to the already-reduced price: $80 → $60 after 25%, then → $48 after the extra 20%. Total effective discount: 40%, not 45%. Retailers know most shoppers add the numbers; now you're not most shoppers.
Quick mental math for the checkout line
- 10% off: move the decimal — $47.90 → $4.79 off.
- 25% off: quarter the price and subtract, or × 0.75.
- 30% off: 3 × the 10% figure.
- Stacked: multiply the "keep" fractions: 25% + extra 20% off = 0.75 × 0.80 = pay 60%.
Is the "deal" actually a deal?
Compare against the lowest recent price, not the inflated "was" price. A genuine benchmark: many retailers cycle 20–30% promotions frequently, so a 40%+ effective discount on something you already planned to buy is usually strong; 10–15% off is marketing noise.
Reading discounts like a retailer
Discount percentages are a pricing tool, not a gift, and knowing roughly what each one does to the seller's margin tells you how much room there is to negotiate — and which "sales" are real.
| Discount | What it usually signals |
|---|---|
| 5–10% | A gesture. Often a loyalty or newsletter incentive with almost no margin impact. |
| 15–25% | Standard promotional range. Most retailers run these several times a year. |
| 30–40% | Genuine seasonal clearance, or a category being cleared for new stock. |
| 50%+ | End-of-line, overstock, or the "was" price was inflated to begin with. |
| 70%+ | Usually below cost — the retailer is recovering cash, not making profit. |
This is why the benchmark that matters isn't the advertised percentage but the lowest recent price. A "40% off" from an inflated reference price can be more expensive than a 15% discount from an honest one. Price-history browser extensions exist for exactly this reason, and in many jurisdictions advertising a "was" price the item never genuinely sold at is illegal — though enforcement is patchy.
Worked examples
Stacked clearance
A $120 jacket at 40% off, with an extra 25% off clearance at the till, in a 13% tax region.
$120 × 0.60 = $72. Then $72 × 0.75 = $54. Effective discount: 55%, not 65%. With tax: $54 × 1.13 = $61.02.
Comparing two offers on the same item
Store A: $80 item, 25% off → $60. Store B: $75 item, $12 off → $63. The bigger-sounding percentage wins here, but only because the base prices differ. Always compare the final price, never the discount.
When a discount isn't a saving
Two traps worth naming. Threshold spending: "spend $100, save $20" is only a saving if you were going to spend $100 anyway — otherwise it's an $80 purchase you hadn't planned. And bulk pricing: buying three of something at 30% off saves nothing if you only use one before it expires. The honest calculation uses what you'll actually consume, not what's in the basket.
For sellers: what a discount costs you
If you're running the promotion rather than shopping it, the arithmetic is sobering. On an item with a 40% margin, a 20% discount doesn't cut your profit by 20% — it cuts it by half. You'd need to roughly double unit sales just to earn the same gross profit. Before discounting, check what volume increase would actually be required; frequently the answer makes a smaller discount, or none, the better decision. Our profit margin calculator shows the effect on your numbers.