Discount Calculator — Sale Price & Stacked Discounts
“30% off, plus an extra 10% at checkout” is not 40% off — it's 37%. Stores count on that confusion. This calculator gives the real final price for single or stacked discounts, plus optional tax, so you know exactly what you'll pay and what you're saving.
How to use this tool
- Enter the tag price and the discount percentage.
- If there's a second \"extra % off\" deal, add it — the tool applies it to the already-reduced price, the way stores actually do.
- Add sales tax if it's charged on top in your country/state.
- Press Calculate to see the true final price and combined discount.
Frequently asked questions
Why isn't 30% + 10% the same as 40% off?
Because the second discount applies to the already reduced price. 30% off 100 → 70; then 10% off 70 → 63. That's 37% total, not 40%. The gap grows with bigger numbers — \"50% + 30%\" is really 65%, not 80%.
How do I quickly estimate a discount in my head?
Anchor on 10%: move the decimal left (10% of 240 = 24). Then scale: 30% = 3 × 24 = 72. For 25%, quarter the price. For odd numbers like 35%, do 25% + 10%.
Is a bigger percentage always the better deal?
Compare final prices, not percentages — 40% off a 300 item (180) still costs more than 20% off a 200 item (160). And check the \"original\" price is genuine: some retailers inflate it before sales. Price-history tools help on big purchases.
Should tax be calculated before or after the discount?
Almost everywhere, sales tax/VAT applies to the price you actually pay — i.e. after discounts. This calculator does it that way. If a store charges tax on the pre-discount price, that's worth questioning.