Sale signs love big percentages, but the price that matters is what you actually pay at the register. The Discount Calculator turns a list price and one or more discounts into the real sale price, the amount you save, and the final total with tax included.
How discounts are calculated
A single discount reduces the price by a percentage of the original. The sale price is what remains after subtracting the discount.
savings = price * (discount% / 100) sale price = price - savings with tax = sale price * (1 + tax% / 100)
Stacked discounts
When discounts stack, each one applies to the already-reduced price, not the original. This is why 20% off followed by 10% off is not 30% off. On a 100 item, 20% off leaves 80, and a further 10% off leaves 72, an effective discount of 28%, not 30%.
Working out a sale price with stacked discounts
- Enter the original price
- Add one or more discount percentages to apply in sequence
- Optionally enter a tax rate to include at checkout
- Read the final sale price and your total savings
Smart shopping checks
- Compare a single big discount against two stacked ones
- See whether a coupon beats a percentage sale
- Add tax to know the true out-the-door price
- Confirm the advertised effective discount is accurate
By showing the math clearly, the Discount Calculator helps you spot genuine bargains and avoid the trap of misleading combined-percentage claims.
Percent off vs flat amount — and the fine print
A percent discount multiplies, so its value in money depends on the starting price; a flat amount (£10 off) is worth the same everywhere. That makes percent-off codes worthless on cheap items and flat codes weak on premium ones. Before you trust a “70% off” claim, also check whether the discount applies per-item or to the subtotal, and whether the seller raised the strike price beforehand — two price-cheat patterns a plain calculator cannot see.
- Compare alternatives: percent off on a mid item vs a flat code on the same cart.
- Check the pre-discount price history for inflate-then-discount.
- Verify the code applies to the items you actually want, not a loss-leader.
