Unit pricing: how to compare UK supermarket loyalty offers

Unit pricing helps UK shoppers compare supermarket offers by showing the cost for a common measure, rather than just the pack. Check that measure alongside any loyalty discount, then consider how much you will actually use. A genuine promotion can still cost more than a suitable alternative or stretch your checkout budget.

• Compare matching units, not just the price printed most prominently.
• Separate a loyalty discount from the question of value elsewhere.
• Check larger packs and multipacks rather than assuming they are cheaper.
• Account for waste, membership conditions and the total shopping bill.

What does unit pricing tell you about a supermarket offer?

The selling price tells you what you pay for the pack. The unit price gives the cost against a common measure, such as a kilogram, litre or individual item. This makes differently sized packs easier to compare without treating a lower checkout price as proof of better value.

According to the Competition and Markets Authority (CMA), in its guide published on 30 January 2024, this information appears on shelf labels and online, usually alongside or beneath the selling price. It may be less prominent than a promotional sign. Look beyond the large headline price before choosing between similar products.

Compare products that meet the same need

A shared measure is useful only when the products are meaningful alternatives. Fresh and concentrated products, different ingredients or different dietary requirements may change what you get from a pack. Start with products you could genuinely substitute, then compare their unit prices.

This article uses UK supermarket evidence, not Canadian pricing rules or a live survey of offers. Canadian readers can use the comparison method where suitable labels are available, but the UK findings below do not establish how Canadian retailers price their products.

How can you compare shelf labels without getting distracted?

Begin with what you need to buy, rather than the discount sticker. For a regular purchase, compare the available sizes and suitable alternatives. The aim is to identify a useful purchase within your budget, not simply the largest advertised reduction.

1. Find the selling price and check which pack it covers.
2. Locate the unit price and read the measurement beside it.
3. Compare alternatives displayed against the same measurement.
4. Check whether a promotional price depends on membership or buying extra items.
5. Choose an amount you can afford, store and realistically use.

If labels use different measures, do not treat the printed figures as directly comparable. Ask a member of staff for help identifying a like-for-like comparison. When shopping online, check the product size and the conditions attached to the offer rather than relying on the search-results thumbnail.

Keep the shelf decision separate from your wider spending plan. Crednine’s guide to managing your finances when prices rise covers the broader household context. A cheaper unit price is useful information, but it does not create extra room in this week’s budget.

Does a loyalty price mean the product is cheapest?

Not necessarily. A member price compares an offer with that retailer’s ordinary price; it does not automatically compare every brand, pack size or competing shop. Treat the promotion as a reason to check, rather than a complete answer.

In findings published on 27 November 2024, the CMA reported that loyalty offers generally delivered real reductions against usual prices. It found little evidence that retailers had raised those usual prices artificially to exaggerate the discount. However, its review also found that loyalty offers were not always the cheapest available option.

Those findings describe the review, not a guarantee about a product on sale today. An own-label equivalent or an offer elsewhere may still be worth checking. Equally, a member price may be a sensible choice if it applies to an item already on your list.

Check whether you can actually receive the offer

Read the membership conditions and confirm that you can present whatever the scheme requires. Consider whether joining suits you, including the information requested. If you cannot access the member price, compare using the price you will actually pay, rather than the more attractive figure on the sign.

Are larger packs and multipacks better value?

The CMA’s unit-pricing work, published on 30 January 2024, challenged common shortcuts for judging supermarket value. Its accompanying guide explained that bigger packs, promotions and multipacks do not necessarily have the lowest unit cost. Checking the label is more reliable than assuming a particular format wins.

Even when a larger pack has a lower unit price, it may not fit your circumstances. Storage space, expiry dates and the amount your household eats all matter. A pack that is economical on paper can be an awkward purchase if much of it remains unused.

A smaller pack may also be the affordable option at checkout. That is a different question from unit value, and neither needs to be ignored. For the wider planning decision, see ways to keep a household budget balanced.

When is comparing another supermarket worth the effort?

Check alternatives when the likely purchase is important enough to justify the effort. A lower product price alone does not settle whether another trip makes sense. Transport, delivery charges, minimum-order conditions and your available time belong in the decision.

Compare a useful basket rather than chasing an isolated deal you did not need. If a promotion encourages extra purchases, pause and return to your original list. The practical question is whether the final basket meets your household’s needs within the amount available.

For a repeat shop, keep brief notes about regularly purchased products and their pack sizes. Refresh the comparison rather than assuming the previous winner remains cheapest: the CMA’s guide notes that unit prices can change over time and differ between shops. This complements planning everyday grocery purchases more deliberately, without requiring you to compare every item on every visit.

Informational content only, not financial advice.