Original price after 10% off
Enter what you paid and this page works back to the pre-sale price. The discount is fixed at 10% — the price is yours to change.
Worked example at 10% off
You paid £45.00 in a 10% off sale.
- 100% − 10% = 90% of the original price remains
- As a decimal that is 0.9
- 45 ÷ 0.9 = £50.00
- You saved £5.00
Check it forwards: £50.00 − 10% = £45.00 ✓
Adding 10% back to £45.00 would give £49.50 — which is wrong, and wrong by more as the percentage grows. The discount was taken off the larger original, so putting it back on the smaller sale price never reaches it.
Where 10% off shows up
Ten percent is the workhorse discount: newsletter sign-up codes, first-order offers, loyalty tiers and student discounts almost all sit here. It is small enough that retailers apply it freely and large enough that shoppers notice, which is why it appears more often than any other single figure.
It is also the most common "stacking" discount — applied on top of an existing sale rather than instead of one. If a code took 10% off an already-reduced price, reversing only the 10% gives you the sale price, not the original ticket price.
10% off price table
What twenty common sale prices were before the 10% reduction. Every figure is divided by 0.9.
| You paid | Original price | You saved |
|---|---|---|
| £8.00 | £8.89 | £0.89 |
| £12.00 | £13.33 | £1.33 |
| £16.00 | £17.78 | £1.78 |
| £20.00 | £22.22 | £2.22 |
| £24.00 | £26.67 | £2.67 |
| £28.00 | £31.11 | £3.11 |
| £32.00 | £35.56 | £3.56 |
| £36.00 | £40.00 | £4.00 |
| £40.00 | £44.44 | £4.44 |
| £44.00 | £48.89 | £4.89 |
| £48.00 | £53.33 | £5.33 |
| £52.00 | £57.78 | £5.78 |
| £56.00 | £62.22 | £6.22 |
| £60.00 | £66.67 | £6.67 |
| £64.00 | £71.11 | £7.11 |
| £68.00 | £75.56 | £7.56 |
| £72.00 | £80.00 | £8.00 |
| £76.00 | £84.44 | £8.44 |
| £80.00 | £88.89 | £8.89 |
| £84.00 | £93.33 | £9.33 |
Doing it without a calculator
The mental shortcut is to add a ninth. You paid 90% of the original, and 1 ÷ 0.9 is 1.111…, so adding roughly an eleventh of what you paid gets you very close. On £45 that is 45 + 5 = £50, which is exact here. The approximation drifts on awkward numbers, so use it to sanity-check the answer rather than to replace it.
The exact method is always the same: divide by 0.9. 10% off leaves 90% of the original, so dividing by 0.9 undoes it precisely. Multiplying, or adding the percentage back on, gives a number that is always too small — and the error grows with the discount.
Frequently asked questions
›Is 10% off the same as dividing by 1.1?
No, and this is the most common error at this rate. Dividing by 1.1 undoes a 10% increase. Undoing a 10% discount means dividing by 0.9, which gives a noticeably larger number.