Discount Calculator
Work out sale prices, savings and percentage discounts with a clean calculator inspired by SUMX.
Work out a discount
Three ways to calculate. Results update as you type, and nothing you enter leaves your browser.
Price after discount
£80.00
- Original price
- £100.00
- You save
- £20.00
- Final price
- £80.00
£100.00 with 20% off is £80.00. You save £20.00.
£100.00 × (1 − 20 ÷ 100) = £80.00
Original price before the discount
£100.00
- Sale price
- £80.00
- Discount amount
- £20.00
- Original price
- £100.00
£80.00 after 20% off means the original price was £100.00.
£80.00 ÷ (1 − 20 ÷ 100) = £100.00
Discount received
20%
- Original price
- £100.00
- Sale price
- £80.00
- You save
- £20.00
£100.00 reduced to £80.00 is a 20% discount.
(£100.00 − £80.00) ÷ £100.00 × 100 = 20%
Need discount calculations on your phone?
SUMX includes discount, percentage and VAT tools inside a clean everyday calculator for Android, with history, favourites and more available with SUMX Pro.
How to calculate a discount
To calculate a discount, multiply the original price by the discount percentage, then subtract that amount from the original price.
£100 with 20% off = £100 − £20 = £80
final price = original price × (1 − discount percentage ÷ 100)
How to calculate the original price before a discount
To calculate the original price from a sale price, divide the sale price by 1 minus the discount percentage.
£80 after 20% off = £80 ÷ 0.8 = £100
original price = sale price ÷ (1 − discount percentage ÷ 100)
This does not work for a 100% discount, because the original price cannot be worked out from a free final price alone.
How to calculate the discount percentage
Subtract the sale price from the original price, divide by the original price, then multiply by 100.
£100 reduced to £80 = (£100 − £80) ÷ £100 × 100 = 20% off
discount percentage = (original price − sale price) ÷ original price × 100
Common discount examples
| Calculation | Result |
|---|---|
| £50 with 10% off | £45 |
| £100 with 20% off | £80 |
| £80 with 25% off | £60 |
| £200 with 30% off | £140 |
| £120 with 50% off | £60 |
| £80 after 20% off | £100 originally |
Discount questions
- How do I calculate 20% off?
- Multiply the original price by 0.8. For example, £100 with 20% off is £80.
- How do I calculate the sale price after a discount?
- Multiply the original price by 1 minus the discount percentage divided by 100.
- How do I find the original price before a discount?
- Divide the sale price by 1 minus the discount percentage. For example, £80 after 20% off was originally £100.
- How do I calculate how much I saved?
- Subtract the sale price from the original price. For example, £100 reduced to £80 means you saved £20.
- How do I calculate the discount percentage?
- Subtract the sale price from the original price, divide by the original price, then multiply by 100.
- Does SUMX include a discount calculator?
- Yes. SUMX includes a discount calculator alongside percentage, VAT and other useful calculator tools.
More SUMX tools: the percentage calculator for percentage change and everyday percentages, the VAT calculator for adding and removing VAT,, the markup & margin calculator for pricing and profit, the unit converter for length, weight and temperature, and the currency converter for exchange rates. If you need a hand with SUMX, the support pages cover getting started, history and troubleshooting. This calculator runs entirely in your browser and sends nothing anywhere; the privacy policy explains how the rest of the site behaves.