Everyday Maths glossary

What is discount?

A discount is a reduction from the original price. It is often shown as a percentage off, a cash saving, or a sale price.

A discount is money taken off the original price. If something costs £100 and has a 20% discount, the saving is £20 and the sale price is £80.

Discounts are usually calculated using a percentage, but they can also be shown as a fixed amount, such as £10 off. The important thing is to compare the final price, not just the headline offer.

Why discounts matter

Discounts matter because they help you work out what you will actually pay and whether a sale offer is genuinely good value. A large-looking percentage can still be less useful than a lower final price or a better unit price.

Original price £100
Discount 20%
Sale price £80

Discount formula

To calculate a percentage discount, multiply the original price by the discount percentage, then subtract the saving from the original price.

Discount amount = original price × discount percentage ÷ 100 Sale price = original price − discount amount

For example, 25% off £60 means £60 × 25 ÷ 100 = £15 off, so the sale price is £45.

Need the sale price quickly?

Use the discount calculator to work out the saving, sale price and effective discount.

Open discount calculator

Percentage discount vs cash discount

A percentage discount changes with the price. A cash discount is a fixed amount off. Neither is automatically better — the better deal is the one that gives the lower final price for what you need.

Offer type Example What to check
Percentage discount 20% off £100 = £20 saving The saving depends on the original price.
Cash discount £15 off £100 = £15 saving The saving is fixed, even if the item price changes.
Unit price deal £3 for 500g vs £5 for 1kg Compare the price per unit, not just the total price.

How stacked discounts work

Stacked discounts are applied one after the other. A 20% discount followed by another 10% discount is not the same as 30% off.

£100 with 20% off = £80 A further 10% off £80 = £72 Total saving = £28 Effective discount = 28%
Common mistake: do not simply add stacked discounts together unless the offer terms clearly say they combine that way.

Discount vs unit price

A discount tells you how much has been taken off. A unit price tells you how much you pay per gram, litre, item or other unit. When comparing groceries or multipacks, unit price is often more useful than discount percentage.

Comparing two offers?

Use the unit price calculator to compare two pack sizes or sale prices on the same unit basis.

Compare unit prices

Common uses of discounts

  • Working out a sale price before buying.
  • Checking how much money a promotion saves.
  • Comparing two offers with different discount percentages.
  • Understanding stacked discounts and voucher codes.
  • Checking whether a reduced item is still good value by unit price.

Related calculators

Discount Calculator Calculate sale price, saving amount and stacked discounts.
Percentage Calculator Work out percentages, increases, decreases and percentage differences.
Unit Price Comparison Calculator Compare offers by price per unit when shopping.
VAT Calculator Add or remove VAT from net and gross prices.

Discount FAQs

What does discount mean?

A discount is a reduction from the original price. It can be shown as a percentage off or a fixed amount off.

How do you calculate a 20% discount?

Multiply the original price by 20 ÷ 100 to find the saving, then subtract that saving from the original price.

Is 20% off then 10% off the same as 30% off?

No. Stacked discounts are usually applied one after the other. On £100, 20% off then 10% off gives a final price of £72, which is a 28% effective discount.

What is the difference between discount and saving?

The discount is the reduction being offered. The saving is the amount of money you keep compared with paying the original price.