Discount Calculator · Practical guide
How to Find the Original Price After a Discount
You know the sale price and the markdown — one division reverses the discount to the original price.
At a glance
The Reverse Discount Formula
If an item was marked down by a percentage and you know the sale price, divide by what remains: Original price = sale price ÷ (1 − discount rate). For 20% off, divide by 0.80; for 25% off, divide by 0.75; for 40% off, divide by 0.60.
Interactive tool
Discount Calculator
Enter your own values, then compare the result with the examples below.
Discount Result
Worked Example
You paid $60 for headphones advertised as 25% off. The original price is $60 ÷ 0.75 = $80. Check it forward: 25% of $80 is $20, and $80 − $20 = $60. The check always works because discounting and reversing are inverse operations.
Common Reverse Calculations
| Sale Price | Discount | Divide By | Original Price |
|---|---|---|---|
| $40.00 | 20% off | 0.80 | $50.00 |
| $60.00 | 25% off | 0.75 | $80.00 |
| $56.00 | 30% off | 0.70 | $80.00 |
| $45.00 | 50% off | 0.50 | $90.00 |
The Classic Mistake to Avoid
Do not add the discount percentage back onto the sale price. If $60 was 25% off, adding 25% of $60 gives $75 — wrong, because the 25% was taken from the original $80, not from $60. Percentages only reverse cleanly when you divide by the remaining fraction. To verify any result, run the original price and discount percentage through the calculator above and confirm you land back on your sale price.
Frequently Asked Questions
Why can't I just add the percentage back to the sale price?
Because the discount was calculated on the original price, not the sale price. Adding 25% of the smaller sale price understates the original — divide by (1 − rate) instead.
How do I find the original price if only a dollar amount was taken off?
Just add it back: original = sale price + dollar discount. If you paid $45 after a $15 coupon, the original was $60.
How do I find the discount percentage from two prices?
Divide the savings by the original price: (original − sale) ÷ original × 100. Dropping from $80 to $56 is (80 − 56) ÷ 80 = 30% off.
Does sales tax change the reverse calculation?
Yes, remove the tax first. If you paid $86.40 total with 8% tax, the pre-tax sale price is $86.40 ÷ 1.08 = $80; then reverse the discount from that figure.