Calculate sale prices and savings instantly
Our free discount calculator helps you quickly find out how much you'll save and what you'll pay after a discount. Whether you're shopping online or in-store, use this tool to make smart purchasing decisions.
Discount Amount = Original Price × (Discount % ÷ 100)
Final Price = Original Price - Discount Amount
Multiply the original price by the discount percentage and divide by 100. For example, a 30% discount on a £50 item: £50 × 30 ÷ 100 = £15 discount. The final price is £50 − £15 = £35. Our calculator does this instantly for any price and discount combination.
Divide the sale price by (1 − discount/100). For example, if an item is £70 after a 30% discount: £70 ÷ 0.70 = £100 original price. This is useful when a sale tag shows the reduced price but not the original.
"Percentage off" means the discount is expressed as a fraction of the original price. A 20% off sale means you pay 80% of the original price. A 50% off sale means you pay half price. The higher the percentage off, the more you save.
Apply the discount first, then add tax. For example, £100 item with 25% off becomes £75. Adding 20% VAT: £75 × 1.20 = £90 final price. Our calculator includes an optional tax field so you can see the total in one step.
Yes. A 30% discount means you pay the remaining 70%. So a £200 item at 30% off costs £200 × 0.70 = £140. Subtract the discount percentage from 100 to find the percentage of the original price you pay — it's a useful mental shortcut when shopping.
A percentage discount reduces a price by a fraction of its original value. The maths is simple — Discount Amount = Original Price × (Discount% ÷ 100), Final Price = Original Price − Discount Amount — but the simplicity hides some practical traps worth knowing about.
Retailers sometimes advertise a percentage off the "original" price that was itself inflated before the sale. This is known as reference pricing, and in the UK it's regulated by the Consumer Rights Act: a "was" price must have been the genuine selling price for a meaningful period. Being able to calculate the actual saving quickly helps you spot whether an advertised discount is as good as it looks.
Stacked discounts work multiplicatively, not additively. A 20% off coupon applied to an item already 30% off does not give you 50% off. Instead: the 30% sale brings a £100 item to £70, then the 20% coupon takes £14 off, leaving £56 — a total saving of 44%, not 50%. Our calculator processes one discount at a time; apply it twice in sequence for stacked discounts.
If you know the sale price and the discount percentage, you can work backwards: Original Price = Sale Price ÷ (1 − Discount% ÷ 100). For example, if an item is £63 after a 30% discount: £63 ÷ 0.70 = £90 original price.
This is useful when a product shows only its sale price and you want to verify the advertised saving, or when calculating what a service originally cost before a loyalty or introductory discount was applied.
In the UK, VAT is applied to the discounted price, not the original. So a £100 item with 20% VAT and a 25% discount costs £100 × 0.75 = £75, then × 1.20 = £90 including VAT. The discount effectively saves you tax as well, since you're paying tax on a smaller base amount. US sales tax works the same way — the tax is calculated on the post-discount price.
A percentage discount reduces the original price proportionally. The formula: discount amount = original price × (discount % ÷ 100). Final price = original price − discount amount. For 25% off a £120 item: discount = £120 × 0.25 = £30; final price = £90.
A faster mental maths approach: multiply the original price by (1 − discount % ÷ 100). For 25% off, multiply by 0.75. For 20% off, multiply by 0.80. For 30% off, multiply by 0.70. This directly gives the final price without calculating the discount separately.
When multiple discounts apply sequentially, the total reduction is not the sum of the individual discounts. A 20% discount followed by a further 10% discount does not equal 30% off — it equals 28% total.
Why: on a £100 item, 20% off gives £80. A further 10% applies to £80 (not £100), giving £72 — a 28% reduction overall. This matters when comparing offers: "20% off then an extra 10% off" is always worse for the buyer than "30% off." The order of stacked discounts doesn't change the final outcome, but their combined effect is always less than their sum.
UK law (Consumer Rights Act 2015 and associated pricing guidance) requires that "was" or "original" prices shown in sales must be the genuine price the item was sold at for a meaningful period before the sale. Artificially inflated reference prices designed to make a discount look bigger are unlawful. The Competition and Markets Authority (CMA) has issued guidance that a reference price should reflect the price charged for at least 28 consecutive days in the previous 6 months at the same outlet.
Online retailers must show the lowest price in the previous 30 days as the reference price under EU Omnibus Directive rules adopted in the UK — this changed how sale prices are displayed from January 2023 onwards.
If you know the original and sale price but not the percentage: discount % = (original − sale) ÷ original × 100. A coat reduced from £180 to £126 represents: (180 − 126) ÷ 180 × 100 = 30% off. This is useful when comparing deals across retailers that express discounts differently, or when evaluating whether a "deal" is genuinely significant.
In the UK, prices shown to consumers include 20% VAT. A discount reduces the VAT-inclusive price — you save proportionally on both the net price and the VAT element. For businesses that reclaim VAT, the actual saving is only on the net price. Some product categories have reduced or zero VAT rates (food, children's clothing, books, energy) — be aware that headline discount comparisons across categories with different VAT rates can be misleading.
Researched and maintained by Iulian, founder of Flux Media Systems. General information, not professional advice — about this site & our sources →