Everyday Money
Reverse Discount Calculator
Know the discounted price and the discount percentage? Recover the original ticket price.
What was the original price?
Useful when a till receipt shows the sale amount and ‘20% off’ but not the pre-sale price — or when checking a claimed discount is real. Enter the final price and discount percentage to recover the original. Forward stacking belongs on discount stacking; percentage puzzles more generally on reverse percentage. After you recover the list price, commercial sense-checks live on discount profitability. Fixed pounds-off vouchers need adding back rather than pure percentage reversal. Arithmetic only — not a complaints procedure for retailers. Journalists and curious shoppers use the same reversal to test whether a ‘was’ price looks plausible against recent trading history. Account teams reconciling credit notes sometimes need the pre-discount figure to match an invoice line. When only an effective percentage is known after stacking, reverse from that combined factor instead of inventing steps. Curious shoppers use the same reversal to test whether a was price looks plausible against recent trading history. Account teams reconciling credit notes sometimes need the pre-discount figure to match an invoice line. When only an effective percentage is known after stacking, reverse from that combined factor instead of inventing imaginary till steps.
Worked example
You paid £80 after ‘20% off’. Original ≈ 80 ÷ (1 − 0.20) = £100. If the receipt also took £5 off with a voucher after the percentage, reverse the voucher first (£85) then divide by 0.8 → £106.25 original before both deals. Always undo in reverse till order.
Limits and assumptions
Assumes the stated percentage applied to the base you think it did. Some tills apply discounts only to eligible lines in a mixed basket. Not consumer-law advice.
Frequently asked questions
How do I reverse a percentage discount?
Original ≈ final ÷ (1 − discount). Example: £80 after 20% off → 80 ÷ 0.8 = £100.
What if two discounts were applied?
Reverse them in opposite order to the till, or use the stacked final price with the combined effective percentage.
Does this work for pounds-off vouchers?
Add the pounds back onto the final price. Percentage reversal alone will not recover a fixed voucher.
Can I check a ‘was/now’ label?
Yes — reverse the claimed percentage from the ‘now’ price and see if it matches the ‘was’ figure.
What about VAT-inclusive sale prices?
Keep everything on the same VAT basis as the receipt; do not mix ex-VAT and inc-VAT figures.