Discount Calculator
Calculate sale prices, discount amounts, and find original prices from discounted amounts. Two-way discount and reverse discount modes
Calculate Discount
Amount Saved
£20.00
Final Price
£80.00
Bulk Discount Reference
| Discount | You Save | Final Price |
|---|---|---|
| 5% | £5.00 | £95.00 |
| 10% | £10.00 | £90.00 |
| 15% | £15.00 | £85.00 |
| 20% | £20.00 | £80.00 |
| 25% | £25.00 | £75.00 |
| 30% | £30.00 | £70.00 |
| 40% | £40.00 | £60.00 |
| 50% | £50.00 | £50.00 |
How Discount Maths Works (and Why It Trips People Up)
A 20% discount on a £80 item gives you £64. The straightforward formula is final = original × (1 - discount/100). Where it gets messy is when discounts stack. A '20% off, then a further 10% off' is not 30% off - it is 28% off, because the 10% applies to the already-discounted price. £80 at 20% off is £64; £64 at a further 10% off is £57.60, an effective 28% saving rather than 30%. Retailers know this and use stacked discounts to advertise bigger numbers than the actual saving warrants.
The reverse calculation matters when something is already on sale and you want to know the real discount rate. If a coat was £180 and is now £108, the saving is £72 and the discount rate is 40%. The formula is rate = (original - final) / original × 100. This is the calculation that exposes the classic 'was £200, now £150' pricing trick when the item was £150 for most of the year before the brief £200 'period of original price' that retailers use to legitimise sales under UK consumer law.
Sales Pricing for Sellers: The Margin Trap
If you are a seller and your gross margin is 40%, a 30% off sale leaves you with 10% margin if your costs are fixed, before processing fees and shipping. If the same product sells through Stripe (1.5% + 20p) or Etsy (6.5% transaction fee plus 0.20 listing), the discounted item can easily go negative. This is why 'Black Friday discounts' are usually clustered around 10-25%; deeper than that and most retailers are losing money per unit, the discount really has to drive volume that compensates.
The reverse problem hits at the high end. A 70% off clearance on premium items often means the products were marked up enormously to begin with so that the 'discount' looks dramatic. UK trading standards require that a 'was' price was the actual selling price for a meaningful period (usually 28 days) before the sale, but enforcement is patchy and many fashion retailers cycle prices in 30-day rotations specifically to keep the higher 'was' figure plausible. Use the reverse calculator to expose what the real price reduction is, not the headline number.
Frequently Asked Questions
What is the difference between markup and discount?
Markup is what a seller adds to cost to set a selling price. Discount is what a seller subtracts from a selling price for a customer. They are not symmetrical. A 50% markup on £10 cost = £15 selling price. A 50% discount on £15 = £7.50, which is a £2.50 loss against the £10 cost. This is why retailers rarely discount more than the markup they originally added, and why doorbusters at 70% off are usually overstock or end-of-line items where the seller would rather take a loss than store it for another year.
Is the discount calculated before or after VAT?
Almost always after. UK consumer-priced goods are quoted inclusive of 20% VAT, and any discount is applied to the inc-VAT price the customer sees. So '30% off £60' means the customer pays £42, and the retailer's VAT obligation reduces proportionally. For B2B transactions where prices are quoted ex-VAT, the discount is applied to the net price first and then VAT is added on the discounted figure. Using the [VAT Calculator](/vat-calculator) helps reconcile the two views.
How do I calculate a percentage off in my head?
For 10%, move the decimal point one place left (£80 becomes £8 off, leaving £72). For 20%, do the 10% trick and double it (£8 doubles to £16 off, leaving £64). For 25%, divide by 4 (£80 / 4 = £20 off, leaving £60). For 50%, halve it. For 33%, divide by 3. Most everyday sale maths can be done with these five fractions plus a bit of mental adding. The calculator handles awkward percentages and stacked discounts that mental maths cannot.
What does '20% off everything' mean exactly?
It usually means 20% off the marked retail price, but read the small print. Common exclusions include sale items already reduced (so you cannot stack the discount), gift cards, certain brands the retailer has agreed not to discount, and any products marked with a yellow or red sticker. The advertised saving is on the original price, not your final spend, so if you buy something already at 30% off, the 20% does not apply on top.
Related Tools
VAT Calculator
Add or remove VAT from any amount instantly. Supports UK standard (20%), reduced (5%) and zero rates. Shows the full net + VAT = gross breakdown.
Profit Margin Calculator
Calculate profit margin and markup from revenue and cost. Understand the difference between margin and markup with clear explanations
Markup Calculator
Calculate selling price from cost and markup percentage, or find your markup from cost and selling price. Shows profit and margin