How to use the discount calculator
- Sale price: enter the original price and the discount to see what you pay and how much you save. Sellers can add their cost to see the margin left.
- Discount %: enter the original and sale prices to find out how big the discount really is.
- Two discounts: for a coupon on top of a sale, enter both and see the true combined discount.
Discount formula
Amount saved = Original price × Discount ÷ 100
Sale price = Original price − Amount saved = Original price × (1 − Discount ÷ 100)
To work out the discount from two prices:
Discount % = (Original price − Sale price) ÷ Original price × 100
Worked example
A jacket costs 80 and is 25% off.
80 × 25 ÷ 100 = 20 saved, so the sale price is 80 − 20 = 60.
If you're the seller and the jacket cost you 30, your margin drops from 62.5% to 50% (60 − 30 = 30 profit, 30 ÷ 60 = 50%).
Stacked discounts aren't added together
"20% off, plus an extra 10% at checkout" sounds like 30% off. It's actually 28%, because the second discount comes off the already reduced price: 100 × 0.8 × 0.9 = 72. The order doesn't change the final price.
What a discount does to a seller's margin
A discount comes straight out of your profit, not your revenue alone. On a product with a 40% margin, a 20% discount halves your profit per sale, so you'd need to sell twice as many to earn the same amount. Before running a sale, check the margin you're left with using the optional cost box, or the profit margin calculator.
| Original margin | Discount | Margin after discount |
|---|---|---|
| 50% | 10% | 44.4% |
| 50% | 20% | 37.5% |
| 40% | 20% | 25% |
| 30% | 20% | 12.5% |
| 30% | 30% | 0% (break-even) |
Frequently asked questions
How do I calculate 30% off?
Multiply the price by 0.7. For example, 30% off 50 is 50 × 0.7 = 35.
Is the discount applied before or after tax?
In most places discounts are applied to the price before sales tax, VAT or GST is calculated, so you pay tax on the lower price. Rules differ by country and by the type of promotion, so check your receipt or local rules.
What's the difference between a discount and a markdown?
They work the same way mathematically. "Markdown" usually describes a permanent price cut by the retailer, while "discount" often means a temporary offer or coupon.
Formulas checked 29 October 2026. This calculator is for planning and education, not financial, tax or legal advice.