What next?
A sale price is only a saving if you check the unit cost and the tax.
How to use this calculator
- Enter the original price.
- Enter the discount — as a percentage, or switch to Amount off for a “£20 off” label (and add any extra stacked discount).
- Read what you pay and how much you save.
What your result means
‘You pay’ is the final price after the discounts; the saving is the difference from the original. Stacked discounts apply one after another, not added together — so 20% then 10% off is 28% off, not 30%.
Why this one is different
A second reduction is taken off the already-reduced price rather than added to the first, and the true discount against the original is reported as one figure. Cash saved and the amount you pay sit beside each other in the currency you chose, so a shelf label can be checked in the shop.
Why "50% off, then 20% off" isn’t 70% off
Stacked discounts feel like they add up — but they multiply. Fifty percent then twenty percent off leaves you paying 40% of the price, a 60% saving, not 70%. Retailers know most shoppers assume the bigger number.
Working out the real final price protects you from clever signage and helps you spot when a "huge" sale is quietly less generous than it looks.
How it works
The discount is taken off the original price to give the sale price. An optional second discount is applied to that reduced price — which is how “extra 10% off sale items” works, and why two stacked discounts never simply add up.
Formula
final = sale × (1 − d₂)
Example calculation
An £80 item at 25% off, plus an extra 10% at the till:
final = 60 × (1 − 0.10) = £54.00
total saving = £26 (not 35%)
Stacked discounts multiply, they do not add
"30% off, then an extra 20% at the till" is not 50% off. The second discount applies to the already-reduced price, so the factors multiply: 0.70 × 0.80 = 0.56, a 44% total reduction. The order does not matter — the result is identical either way — but the difference from the intuitive answer is large enough to change a buying decision. The same arithmetic works in reverse for a discount followed by a surcharge, which is why a "20% off plus 20% delivery" offer leaves you paying 96% of the original.
Working back to the original price
If you know the sale price and the discount rate, divide rather than multiply: £48 after 40% off is 48 ÷ 0.60 = £80 before. This is the calculation that checks whether an advertised "was" price is real, and it is also how to work out the discount you need to hit a target spend. Beware percentage-off claims quoted against a recommended retail price no one charges — the honest comparison is against the price the item actually sold at recently, not against a list figure.
Frequently asked questions
Is 50% off then 10% off the same as 60% off?＋
No — stacked discounts multiply, not add. 50% then 10% off leaves you paying 45% of the original, a 55% total discount, not 60%.
What is the effective discount?＋
It's the total saving as a percentage of the original price, after any stacked discounts.
How do I work out the original price from a sale price?＋
Divide by one minus the discount. A jacket at 60 pounds after 25 percent off was 60 divided by 0.75, or 80 pounds.
Is buy one get one free the same as 50 percent off?＋
Only if you want two. Per item it is a 50 percent saving, but the outlay is the full price of one item and you leave with a second you may not need.
How do I compare a percentage discount with a fixed amount off?＋
Convert the fixed amount to a percentage of the price. Ten pounds off a 40 pound item is 25 percent; the same tenner off a 200 pound item is 5 percent.
What is three for two worth as a percentage?＋
A third off, or 33.3 percent, provided all three items cost the same. If they differ, most offers give the cheapest free, which lowers the effective saving.
Related calculators
Further reading
Assumptions & limitations
The arithmetic is exact; the shop is where it gets complicated.
- Percentages are applied to the price you enter. If a shelf price already includes an earlier reduction, the saving shown is against that reduced price, not the original.
- Stacked discounts are applied one after another, which is how retailers actually do it — 50% then 20% off is 60% off in total, not 70%.
- Sales tax and VAT are not handled. Enter tax-inclusive prices if you want a tax-inclusive answer.
- Rounding follows normal currency rules, so a long chain of percentages can differ by a penny from a till receipt.
Sources & references
Discount and pricing terminology on this page follows UK consumer-law definitions of a genuine price reduction:
- Department for Business & Trade — pricing practices guidance for traders
- Which? Consumer Rights — reference pricing and sale claims