Work out the real price when a sale, an extra percent-off code and a dollar coupon are stacked – plus sales tax – and see the true percent off, not the headline.
By TanLabs · Formulas cross-checked against the free spreadsheet · Updated 2026-10-31 · Runs in your browser – nothing you type is sent anywhere
With original price $200, sale discount 25%, extra code at checkout 10%, dollar coupon $10, sales tax 7%:
You pay $125.00 before tax, $133.75 with tax
You save $75.00 = 37.5% off (the headline sum would be 35% + $10.00)
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Each percent discount applies to the price left after the previous one: price × (1 − d1) × (1 − d2). The dollar coupon comes off after that, then sales tax is added. True % off = (original − final pre-tax price) ÷ original.
The same $100 item under common Black Friday and Cyber Monday offers:
| Offer on a $100 item | Sounds like | Really | You pay |
|---|---|---|---|
| 20% + 10% | 30% | 28.0% | $72.00 |
| 25% + 10% | 35% | 32.5% | $67.50 |
| 30% + 20% | 50% | 44.0% | $56.00 |
| 40% + 20% | 60% | 52.0% | $48.00 |
| 50% + 50% | 100% | 75.0% | $25.00 |
| 25% + 10% + $10 | 35% + $10 | 42.5% | $57.50 |
| $10 coupon first, then 25% + 10% | 35% + $10 | 39.25% | $60.75 |
"50% + extra 50%" sounds free but is 75% off. A dollar coupon is worth more when it comes off after the percentages, which is how most stores apply it.
No. The second discount applies to the already reduced price: $100 × 0.75 × 0.90 = $67.50, which is 32.5% off.
Not between two percentages. It does matter for a dollar coupon: $10 taken off before the percentages saves less than $10 taken off after them. Enter it the way your receipt shows.
In most US states on the price you actually pay after store discounts. Manufacturer coupons can be taxed differently in some states.
Buy-one-get-one-free is 50% off only if you wanted two. "Buy one, get one 50% off" is 25% off the pair.
Many stores allow one store coupon plus one manufacturer coupon per item. Check the store's coupon policy page.
Look at a price-history tool or the price a month before the sale. If the "was" price never appeared, compare with other stores instead.
Sources: eCFR – 16 CFR Part 233, FTC Guides Against Deceptive Pricing