Discount Calculator UK
Calculate sale prices, percentage off and how much you save. Switch to reverse mode to find the original price from a sale price.
Quick Discount Reference Table
How much do you save at common discount percentages? The table below shows the sale price and savings for popular price points.
| Original Price | 10% Off | 20% Off | 25% Off | 30% Off | 50% Off |
|---|---|---|---|---|---|
| £10.00 | £9.00 (save £1) | £8.00 (save £2) | £7.50 (save £2.50) | £7.00 (save £3) | £5.00 (save £5) |
| £25.00 | £22.50 (save £2.50) | £20.00 (save £5) | £18.75 (save £6.25) | £17.50 (save £7.50) | £12.50 (save £12.50) |
| £50.00 | £45.00 (save £5) | £40.00 (save £10) | £37.50 (save £12.50) | £35.00 (save £15) | £25.00 (save £25) |
| £100.00 | £90.00 (save £10) | £80.00 (save £20) | £75.00 (save £25) | £70.00 (save £30) | £50.00 (save £50) |
| £200.00 | £180.00 (save £20) | £160.00 (save £40) | £150.00 (save £50) | £140.00 (save £60) | £100.00 (save £100) |
| £500.00 | £450.00 (save £50) | £400.00 (save £100) | £375.00 (save £125) | £350.00 (save £150) | £250.00 (save £250) |
How to Calculate a Discount
The core discount formula is straightforward:
For example, to calculate 30% off £85:
- Convert the percentage to a decimal: 30% = 0.30
- Subtract from 1: 1 - 0.30 = 0.70
- Multiply: £85 × 0.70 = £59.50
- Amount saved: £85 - £59.50 = £25.50
Alternatively: Amount Saved = £85 × 0.30 = £25.50, then Sale Price = £85 - £25.50 = £59.50.
Finding the Original Price (Reverse Discount)
If you know the sale price and the discount percentage, you can find the original price:
Example: An item is on sale for £72 after a 20% reduction. What was the original price?
- 1 - 0.20 = 0.80
- £72 ÷ 0.80 = £90
The original price was £90. This is useful for checking whether a claimed "was" price in a sale is genuine.
Finding the Discount Percentage
If you know both the original price and the sale price:
Example: Originally £120, now £84. Discount = ((£120 - £84) ÷ £120) × 100 = (£36 ÷ £120) × 100 = 30%.
Common UK Discount Scenarios
Black Friday and Seasonal Sales
Black Friday (the last Friday of November) has become one of the UK's biggest shopping events, with discounts typically ranging from 10% to 70% across electronics, clothing, appliances and more. UK consumer law requires that sale reference prices must represent genuine previous selling prices — the Competition and Markets Authority (CMA) has issued guidance that the "was" price should reflect a price charged for at least 30 consecutive days before the promotion. Our discount calculator helps you verify whether a claimed saving is accurate.
VAT and Price Discounts
Most UK retail prices already include 20% VAT. When a discount is applied, it reduces both the net price and the VAT proportionally. If you need the ex-VAT sale price, divide the sale price by 1.20 (or multiply by 5/6). For example: £96 sale price ÷ 1.20 = £80 ex-VAT.
Student and NHS Discounts
Many UK retailers offer student discounts (typically 10%-20% via UNiDAYS or Student Beans) and NHS staff discounts. These work exactly like standard percentage discounts — enter the retail price and discount percentage into our calculator to find your price instantly.
Stacking Discounts
When two discounts apply sequentially (not combined), the total saving is greater than the sum of the percentages. For example, 20% off followed by an additional 10% off: Start with £100 → 20% off = £80 → 10% off £80 = £72. Total saving = £28 (28%), not 30%. Beware retailers who advertise stacked discounts ambiguously.
Frequently Asked Questions
How do I calculate 20% off a price?
Multiply the original price by 0.80 to get the sale price directly, or multiply by 0.20 to find the amount saved. For example, 20% off £50: Sale price = £50 × 0.80 = £40. Amount saved = £50 × 0.20 = £10.
How do I work out a discount percentage?
Use the formula: Discount % = ((Original Price - Sale Price) ÷ Original Price) × 100. If an item was £80 and is now £60: ((£80 - £60) ÷ £80) × 100 = 25% off.
How do I find the original price before a discount?
Divide the sale price by (1 - discount as a decimal). Example: sale price £75, discount 25%: £75 ÷ 0.75 = £100 original price. Use the "Find Original Price" tab in our calculator above.
What is the formula for discount?
Sale Price = Original × (1 - Discount%/100). Amount Saved = Original × (Discount%/100). Discount% = ((Original - Sale) ÷ Original) × 100. Original = Sale ÷ (1 - Discount%/100).
How do I calculate a discount including VAT?
UK retail prices include 20% VAT. Apply the discount to the full VAT-inclusive price to get the sale price. To find the ex-VAT element, divide the sale price by 1.20. For example: £120 with 25% off = £90 sale price. Ex-VAT = £90 ÷ 1.20 = £75.
Are UK sale discounts regulated?
Yes. The Consumer Protection from Unfair Trading Regulations require reference prices to be genuine. The CMA guidance states a "was" price should reflect the price charged for at least 30 consecutive days. Misleading discounts can lead to Trading Standards enforcement action.