Discount Calculator

This calculator works out the final price after a percentage discount, the amount you save and — for stacked discounts — the combined effective percentage off. Enter the original price and one or more discount percentages to see results instantly.

Stacked discounts are applied sequentially, not added together. A 20% discount followed by a 10% discount is not 30% off — it is 28% off because the second discount applies to the already-reduced price. The calculator handles this correctly and shows the true combined saving.

You can also reverse-calculate: enter the sale price and original price to find the percentage discount that was applied. This is useful for checking whether a sale is genuine or whether the original price was inflated.

The discount formula explained. Sale price = original × (1 − discount/100). To find original price from a sale price: original = sale ÷ (1 − discount/100). £60 marked '25% off' means original was £80 (£60 / 0.75). Savings = original × discount/100. Mental shortcuts: 10% = divide by 10; 25% = divide by 4; 33% = divide by 3; 50% = halve; 75% = three-quarters; 90% off = price × 0.1.

Stacking discounts — beware of false advertising. Two discounts stack multiplicatively, not additively. '20% off then extra 10%' = 28% off, NOT 30% (0.80 × 0.90 = 0.72). '50% + 25%' = 62.5% off, not 75%. Order of operations doesn't matter mathematically, but retailers sometimes apply codes only to specific items, or only after sale prices. Black Friday hype often markets 'up to 80% off' where the headline applies to a few clearance items only.

UK 'was/now' pricing law. Consumer Protection from Unfair Trading Regulations 2008 require honest reference pricing. The 'was' price must reflect a genuine higher price the item was sold at for a meaningful prior period — usually 28+ consecutive days within the previous 6 months. Trading Standards investigate complaints; misleading pricing can void the sale and trigger ASA rulings. Tools to verify: CamelCamelCamel (Amazon UK price history), PriceSpy, Idealo — show 90-day price tracking across major retailers.

VAT and discounts — order matters. On VAT-inclusive prices (B2C shops): discount applies to gross price, VAT is already embedded. £120 at 20% off = £96 (VAT was £20, now £16). On VAT-exclusive prices (B2B invoices): discount applies to net, then VAT added. £100 net − 20% = £80, +20% VAT = £96 gross. Trade discounts and bulk-purchase discounts reduce VAT base. Settlement (prompt-payment) discounts: VAT must reflect what's actually paid — adjust invoice if customer takes the discount.

Best UK shopping discount strategies. Sign up for retailer emails — first-order codes typically 10-15% off. Wait for Bank Holiday weekends (May, August), Black Friday (late Nov), Boxing Day-January for white goods/clothing. Use cashback sites (TopCashback, Quidco) on top of discount codes — often stack 3-8% additional. Loyalty stacking: Tesco Clubcard prices give 50% off select items to members. Student discount (UNiDAYS, Student Beans) adds 10-15% across major retailers — valid up to 25 in many cases.