How Do You Find the Original Price from a Sale Price?

The Reverse Percentage Formula

When you see a sale price and want to know what the item originally cost — or to verify a retailer's claim — the formula is:

• Original price = sale price ÷ (1 − p/100)

For a $60 item marked 25% off: original = 60 ÷ (1 − 0.25) = 60 ÷ 0.75 = $80. That means the retailer should have been selling it at $80 before the sale. If the tag or website claims the original was $120, that's a red flag worth investigating — the math says $80, not $120.

More worked examples:

• Sale $45, 10% off → original = 45 ÷ 0.90 = $50
• Sale $70, 30% off → original = 70 ÷ 0.70 = $100
• Sale $63, 40% off → original = 63 ÷ 0.60 = $105

Is the Deal Real? Spotting Inflated 'Original' Prices

Some retailers inflate the “original” or “compare at” price to make a discount look bigger than it is. A jacket listed at $200 “original” and now $120 suggests 40% off — but if that jacket was only ever sold at $120, the $200 is a manufactured reference price, not a genuine markdown.

How to sanity-check:

• Use the reverse formula: sale price ÷ (1 − claimed discount) should equal the claimed original. If the numbers don't match, question the deal.
• Search for the item at other retailers to see if the “original” price is consistent.
• Check whether the retailer has sold the item at that original price recently — not just used it as a label.

The reverse formula doesn't expose dishonesty on its own, but it does let you instantly verify whether the arithmetic at least adds up before you decide to trust the advertised markdown.

Using the History Tab to Compare Prices Over Time

Discount Calculator: % Off saves every calculation automatically to a private History tab on your device, grouped by date and searchable. This is useful for reverse-discount thinking: if you calculated a price on one shopping trip, you can look it up later and compare it against what you find on a return visit or at a different store.

For example, you scan a price tag, calculate the discounted price, and save it. A week later the same item is “further reduced.” Open History, find last week’s result, and see whether the new “original” and new discount actually land at a lower price than what you saw before — or whether the retailer simply re-labeled the same end price with a different story. All on-device, no account required, completely private.