About this calculator
Use this discount calculator to see the sale price after a percentage off, how much you save, or what percentage discount you're actually getting.
It also handles the “extra 10% off” situation, where a second discount is taken off the already-reduced price, and it can work backwards from a sale price to the original price.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
30% off £200
- Sale price
- £140.00
- You save
- £60.00
30% off £200.00 is £140.00, saving you £60.00.
20% off £100, then a further 10% off
- Sale price
- £72.00
- You save
- £28.00
- Total discount
- 28%
20% off, then a further 10% off, takes £100.00 down to £72.00. That's 28% off in total, not 30%.
Was £80, now £60
- Discount
- 25%
- You save
- £20.00
Going from £80.00 to £60.00 is a 25% discount.
How discounts are calculated
Sale price = original price × (1 − discount). 30% off £200 is £200 × 0.7 = £140, so you save £60.
Discount percentage = (original − sale) ÷ original × 100. Was £80, now £60: a £20 saving on £80 is 25%.
Original price = sale price ÷ (1 − discount). If £75 is the price after 25% off, the original was £75 ÷ 0.75 = £100.
Two discounts don't add up
“20% off, then an extra 10% off” is not 30% off. The second discount applies to the already-reduced price. £100 becomes £80, and 10% off £80 is £72, so the total discount is 28%. The more discounts you stack, the further the total falls short of simply adding them.
Discounts and VAT
Because VAT is a fixed percentage of the net price, a percentage discount gives the same result whether you take it off the price before VAT or the price including VAT. 20% off £120 (including VAT) is £96, which is exactly the same as 20% off £100 plus VAT.
Frequently asked questions
How do I calculate 20% off?
Multiply the price by 0.8. For 30% off, multiply by 0.7. For any discount, multiply by 1 minus the discount as a decimal.
How do I work out the discount percentage from two prices?
Subtract the sale price from the original, divide by the original price, and multiply by 100. Was £80, now £60 is 20 ÷ 80 = 25% off.
Are two discounts added together?
No. They multiply. 20% off followed by 10% off is 28% off in total, not 30%.
How do I find the original price after a discount?
Divide the sale price by 1 minus the discount as a decimal. If £75 is 25% off, the original was 75 ÷ 0.75 = £100. Don't add 25% to £75: that gives £93.75.
Does the discount come off before or after VAT?
A percentage discount gives the same result either way, because VAT is also a percentage. A fixed amount discount, such as £10 off, does differ.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.