Discount Calculator
Find the sale price after a percentage discount, how much that saves you, or work backwards to the original price.
Sale price from original + discount
Original price from sale price + discount
The two directions of this calculation
Going forward, the sale price is the original price minus the original price times the discount rate. Working backward from a sale price to the original, dividing by the discount rate directly would be wrong — instead the sale price is divided by (1 − discount rate), since the sale price already reflects the discount having been removed.
Common uses
- Comparing "% off" deals across different stores quickly
- Checking whether a "was" price advertised alongside a sale price is accurate
- Working out the pre-tax or pre-discount price for expense reporting
Frequently asked questions
How do I calculate a 20% discount on a price?
Multiply the original price by 0.20 to find the amount saved, then subtract that from the original price — for example, 20% off $50 saves $10, making the sale price $40. The first calculator above does this instantly.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount rate as a decimal) — for example, if $80 is the price after a 20% discount, the original price is 80 ÷ 0.80 = $100. Use the second calculator above for this.
Why can't I just add the discount percentage back to the sale price?
Because the discount percentage applies to the original price, not the sale price — adding 20% of the sale price back doesn't equal the original price. Dividing by (1 − discount rate) correctly reverses the calculation.
How do I compare two different percentage-off deals?
Calculate the actual sale price for each deal using the first calculator, then compare the resulting prices directly — a bigger percentage off a higher original price isn't always the better deal in absolute terms.