Percentage Off Calculator

How it works

A percentage off means the price is reduced by a proportion of the original. To find out how much you save, convert the percentage to a decimal and multiply by the original price. Subtract the saving from the original to get the sale price.

The formula

You can also calculate the sale price in one step: multiply the original price by (1 - % Off / 100). For example, 25% off means you pay 75% of the original.

Why this works: A percentage off represents a fraction of the original price you do not pay. Multiplying the original by that fraction gives the saving. Subtracting the saving from the original gives the amount you do pay. The one-step shortcut (multiplying by the complement) combines both steps into a single calculation.

Worked examples

The psychology of percentage-off deals

Retailers know that "25% off" and "save £30" trigger different reactions in the brain even when they describe exactly the same deal. Research consistently shows that percentage framing feels more impressive on lower-priced items (a 30% saving on a £15 candle sounds big) while a cash saving lands harder on higher-priced ones (saving £600 on a £2,000 sofa feels more real than "30% off"). Understanding this helps you cut through the marketing and focus on the number that matters to your budget.

Reference prices are at the heart of every "was/now" promotion. UK Advertising Standards Authority (ASA) guidelines require that a "was" price must have been the genuine selling price for a meaningful period. A product cannot be inflated to £200 for a week and then advertised as "50% off" at £100. If a deal seems unusually large, it is worth checking how long the item was sold at the reference price.

A practical test: cover the "% off" badge and the "was" price. Ask yourself whether you would buy the item at the sale price on its own merits. If the answer is yes, it is a genuine deal for you. If you would not have considered it without seeing the original price, the discount is doing more emotional work than financial work.

When to use this

Percentage-off calculations come up constantly in UK retail and services:

• Seasonal sales and Black Friday: A laptop listed at £1,199 with 20% off costs £959.20, saving £239.80. Calculating the precise saving lets you compare across retailers who may advertise different base prices for the same product.
• Student and loyalty discounts: Many UK retailers offer 10-20% off for students via TOTUM or for NHS and Blue Light Card holders. On a £150 pair of boots with 15% off, the saving is £22.50 and you pay £127.50. Worth checking against other retailers without the discount before assuming it is the best deal.
• Subscription introductory offers: Broadband and streaming providers often advertise 40-50% off for the first 6 or 12 months. On a £38 per month broadband plan, 40% off saves £15.20 per month, or £91.20 over a 6-month intro period. Knowing the exact figure helps you budget before the full price kicks in.
• Trade discounts: Builders, plumbers, and electricians typically receive 20-30% trade discount from merchants. On a £2,400 bathroom suite, a 25% trade discount saves £600. Verifying the exact amount prevents billing errors on larger orders.

Understanding the result

The sale price and saving scale in direct proportion to the original price. A 25% off deal always means you pay 75% of the original, whether the item costs £10 or £10,000. What changes is the absolute saving. This is why percentage-off can feel abstract compared to seeing the cash amount: 5% off a £500 laptop (£25) and 5% off a £10 pair of socks (50p) are the same percentage, but they feel completely different.

Watch out for stacked discounts. A further 10% off a price already reduced by 20% does not equal 30% off the original. You save 20% first, bringing the price to 80% of original, then 10% of that reduced price. The combined saving is 28%, not 30%. Always apply each discount step by step.

Related concepts

➡ If you know the sale price but not the original, the reverse percentage calculator works backwards from any sale price to find what it cost before the reduction. ➡ When deals are advertised as a cash saving rather than a percentage, the discount calculator converts the pound saving into a percentage of the original price. ➡ To see the same price drop expressed as a percentage fall, the percentage decrease calculator shows the reduction as a rate relative to the starting value.

How to do this in Excel

Put the original price in A1 and the percentage off in B1. The formula multiplies the original by the proportion you still pay. To show the saving separately, use =A1*B1/100 in an adjacent cell. For a list of items, copy the formula down column C and use =SUM(C1:C10) to total the savings.

How to do this without a calculator

Find 10% of the original price by dividing by 10. Scale up or down from there. For 25% off a £120 item: 10% = £12, 20% = £24, 5% = £6, so 25% = £30 saving. Sale price = £120 - £30 = £90. For 15% off, find 10% and add half of 10% to get 15%. This mental arithmetic works well for round prices and common discount percentages like 10%, 20%, 25%, and 50%.

Real world uses

• Calculating the price of an item in a Black Friday, Boxing Day, or January sale.
• Checking what you pay for clothing after a student or loyalty discount is applied.
• Working out the advance booking price for a hotel, flight, or train ticket.
• Finding the monthly cost of a subscription plan after an introductory discount.
• Verifying the saving on any item before adding it to your online basket.

Common mistakes

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