How to calculate a discount
- Enter the original price and the percentage off. The sale price and the amount saved appear instantly.
- For "an extra 10% off sale prices" deals, enter the second discount too: discounts stack by multiplying, not adding.
- Add a quantity or sales tax to get the final total. Shop owners can enter their unit cost to see how the discount changes their margin.
- Use "Work backwards" to find the discount needed to reach a target price.
Discount maths that catches people out
A discount of 25% on 80 takes off 80 × 0.25 = 20, leaving 60. Stacked discounts are applied one after another, so 25% off followed by an extra 10% off is 80 × 0.75 × 0.9 = 54, a total of 32.5% off, not 35%. Likewise, a price that is cut by 50% and then raised by 50% ends up 25% below where it started.
For sellers, discounts cost more than they look. If an item costs you 40 and sells for 80, your profit is 40 per sale. Take 25% off and the profit falls to 20, so you must sell twice as many units just to make the same money. The margin panel shows this break-even sales increase, which is a useful check before launching a promotion. Consider alternatives such as bundles, free shipping thresholds or a gift with purchase, which can protect margins better than straight price cuts. All calculations run in your browser and work in any currency.
How do I calculate 20% off?
Multiply the price by 0.8. For example, 20% off 45 is 45 × 0.8 = 36.
Are two 10% discounts the same as 20% off?
No. Two 10% discounts give 19% off in total, because the second applies to the already reduced price.
Is sales tax charged before or after a discount?
Usually after: tax is calculated on the discounted price. Some coupon rules vary by country or state.