Learn how to find a sale price, work backward to an original price, and correctly stack two discounts together.
Whether you’re shopping a sale or pricing one, calculating a discount comes down to one percentage formula applied in a specific direction. Here’s how to find a sale price, work backward to an original price, and stack multiple discounts correctly.
To find the price after a discount, first find the discount amount, then subtract it from the original price:
For a $80 item at 25% off: the discount amount is 80 × 0.25 = $20, so the sale price is 80 − 20 = $60.
A faster one-step version: multiply the original price by (100% − discount%). For the same example, that’s 80 × 0.75 = $60.
If you know the sale price and the discount percentage, and want the original price, divide instead of multiply:
If an item costs $60 after a 25% discount: 60 ÷ (1 − 0.25) = 60 ÷ 0.75 = $80.
Two discounts don’t simply add together. A 20% discount followed by a 10% discount is NOT a 30% discount overall — each discount applies to the price that’s already been reduced by the previous one.
For a $100 item with 20% off, then an extra 10% off: 100 × 0.80 × 0.90 = $72, not $70. The combined effective discount is 28%, not 30%.
A discount is really just a percentage decrease applied to a price: see How to Calculate Percentage Decrease for the general formula behind it, and Markup vs Margin if you’re pricing from the seller’s side rather than the buyer’s.
| Original Price | Discount | Sale Price |
|---|---|---|
| $50 | 10% | $45.00 |
| $120 | 25% | $90.00 |
| $200 | 15% then 10% | $153.00 |
Discount Calculator
Multiply the original price by the discount rate as a decimal to get the discount amount, then subtract that from the original price to get the sale price.
Divide the sale price by (1 minus the discount rate as a decimal). For a $60 sale price after a 25% discount, divide 60 by 0.75 to get an original price of $80.
No. Each discount applies to the already-reduced price, not the original price, so two stacked discounts always add up to slightly less than their sum — a 20% and a 10% discount together give 28% off, not 30%.
Not unless you add it separately. Discounts are typically applied to the pre-tax price, with tax calculated afterward on the discounted amount, though this can vary by location.
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