Original Price Calculator
Enter what you paid and the discount to see the pre-sale price and your actual saving.
Working back from a sale price
A discount is taken off the original, so the price on the tag is a fraction of what the item cost before. At 25% off you paid 75% of the original — divide by 0.75 to get back.
A coat is £210 in a 20% off sale.
- 80% of the original remains
- 210 ÷ 0.8 = £262.50
- You saved £52.50
Adding 20% back to £210 gives £252 and understates the saving by £10.50. The discount came off the bigger number, so putting it back on the smaller one never reaches it.
"Extra 20% off already-reduced prices"
Stacked discounts multiply — they do not add. A 30% sale followed by an extra 20% leaves 0.7 × 0.8 = 0.56 of the original, so the total reduction is 44%, not 50%. To reverse it, divide by 0.56 once rather than undoing each step and rounding twice.
The gap widens with the numbers. "50% off, then 50% off" sounds like free and is actually 75% off. Shops are not being dishonest with this wording, but it does reliably read as more generous than it is.
Is the discount genuine?
Reversing the percentage tells you the price the shop is claiming the item used to cost. Whether it ever actually sold at that price is a different question, and one worth asking when the discount is unusually large.
UK pricing guidance expects a reference price to have been the genuine selling price for a reasonable period before the sale. A permanent "was £200, now £80" on an item that has never left the sale rack is the pattern regulators look at. You cannot verify that from the tag alone, but knowing the implied original gives you something concrete to check against the price elsewhere.
The reverse also matters when the saving is what is advertised rather than the percentage. "Save £45" on a £135 price is a 25% discount off £180 — dividing tells you the depth of the reduction, which is the number that lets you compare two offers that are quoted differently.
Common discounts at a glance
| Discount | Divide sale price by | £60 paid means it was |
|---|---|---|
| 10% off | 0.90 | £66.67 |
| 15% off | 0.85 | £70.59 |
| 20% off | 0.80 | £75.00 |
| 25% off | 0.75 | £80.00 |
| 30% off | 0.70 | £85.71 |
| 40% off | 0.60 | £100.00 |
| 50% off | 0.50 | £120.00 |
| 60% off | 0.40 | £150.00 |
| 70% off | 0.30 | £200.00 |
| 75% off | 0.25 | £240.00 |
Frequently asked questions
How do I find the original price before a discount?
Divide the sale price by 1 minus the discount as a decimal. A £45 jacket at 25% off was 45 ÷ 0.75 = £60 before the sale.
How much did I actually save?
The saving is the original price minus what you paid. On that £60 jacket bought for £45, the saving is £15 — which is 25% of £60, not 25% of £45.
A shop says "extra 20% off sale items". How do I reverse that?
Two discounts multiply rather than add. A 30% sale then an extra 20% is 0.7 × 0.8 = 0.56, so divide the final price by 0.56. That is 44% off in total, not 50%.
Can I check whether a sale price is genuine?
Reversing the advertised discount tells you the price the shop is claiming as the original. Whether the item ever sold at that price is a separate question, and one worth asking about very large discounts.