Discount Calculator guide
Discount Calculator: Sale Price and Percent Off
Use our discount calculator to work out the sale price and saving from a percentage off, including an extra discount, or find the original price.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
How much is 30% off? And what about an extra 10% on top? Our Discount Calculator works out sale prices in a second.
How to use the calculator (Discount Calculator)
- Choose whether you know the original price or the sale price.
- Enter the price and the discount.
- Add an extra discount if there's one on top.
The formulas
- Sale price = original × (1 − discount ÷ 100)
- Original price = sale price ÷ (1 − discount ÷ 100)
Stacked discounts
Two discounts don't simply add up. 30% off then an extra 10% off is:
1 − (0.7 × 0.9) = 37% off, not 40%.
A worked example
With the calculator's default settings, 30% off £80 is £56, saving £24.
Frequently asked questions
How do I work out the percentage discount?
Divide the saving by the original price and multiply by 100. Use our Percent Change Calculator.
Is the "was" price genuine?
UK rules say reference prices must be genuine. Be wary of prices that were only charged briefly.
Sources and further reading
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.