Shopping maths
How to Calculate a Discount
A shopper-friendly guide to sale prices, percentage-off offers, stacked discounts, and the difference between savings and final price.
A discount reduces an original price by a percentage or fixed amount. To check the sale price and savings quickly, enter the original price and discount in the discount calculator.
The short version
For a percentage discount:
Discount amount = original price x discount percentage / 100
Sale price = original price - discount amount
If an item costs 120 and the discount is 25%, the saving is 30 and the sale price is 90.
Try it with your own numbers
Use the discount calculator for sale prices and savings. If you need to compare the old and new price after the fact, use the percentage increase calculator or percentage calculator.
How the calculation works
Convert the percentage into a decimal, multiply by the original price, then subtract that saving from the original price.
For multiple discounts, apply them in sequence unless the offer says they are added together. A 20% discount followed by a 10% discount is not the same as a single 30% discount.
A worked example
An appliance costs 450 and has a 15% discount.
- Discount amount: 450 x 15 / 100 = 67.50
- Sale price: 450 - 67.50 = 382.50
The customer saves 67.50 and pays 382.50 before any delivery, tax, or extra fees.
Watch-outs
- Applying the discount to the wrong starting price.
- Adding two discounts together when they apply one after another.
- Forgetting delivery charges or VAT treatment.
- Comparing discounts without checking the final price.
- Treating cashback as an instant discount when it is paid later.
How to read the result
Use discount calculations for shopping, quotes, invoices, and promotions. For business pricing, check margin separately because a discount can reduce profit faster than it appears from the headline percentage.
Tools mentioned in this article
Reader questions
Is 20% off then 10% off the same as 30% off?
No. The second discount is applied to the already reduced price, so the combined reduction is 28% in that example.
How do I calculate the original price from a sale price?
Divide the sale price by 1 minus the discount rate. For 25% off, divide by 0.75.
Should VAT be added before or after a discount?
It depends on how the price is quoted and local tax rules. For UK VAT questions, use the VAT calculator as a separate check.
Why do small discounts matter to margin?
A discount reduces revenue directly, while many costs stay the same. That can shrink profit margin quickly.
