How to calculate a discount
Sale price = price × (1 − discount%/100)
A £80 item at 25% off saves £20, so you pay £60.
Stacking discounts
Stacked discounts multiply, not add. A 20% then 10% discount is not 30% off — it's 0.8 × 0.9 = 0.72, or 28% off the original price.
Frequently asked questions
How do I calculate percent off?
Multiply the price by the percentage as a decimal. 30% off £50 = £50 × 0.30 = £15 saved, leaving £35.
Are stacked discounts the same as adding them?
No. 20% + 10% stacked is 28% off, not 30%.
How do I work out the original price from a sale price?
Divide the sale price by (1 − discount). A £60 item at 25% off had an original price of 60 ÷ 0.75 = £80.