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Unit Pricing: Your Complete Guide to Smart Shopping in the UK

Unit pricing is one of the most powerful tools available to UK consumers for making informed purchasing decisions, yet many shoppers overlook or misunderstand the unit price labels displayed on supermarket shelves. A unit price expresses the cost of a product per standard unit of measurement (per kilogram, per litre, per 100 grams, per 100 millilitres, or per item), allowing direct comparison between products of different sizes and brands.

Under UK pricing regulations (the Price Marking Order 2004, updated 2015), most retailers are legally required to display unit prices alongside the selling price for pre-packaged goods. The unit must be appropriate to the product: foods are typically priced per kilogram or per 100 grams, beverages per litre or per 100 millilitres, and items sold in discrete units (like dishwasher tablets) per item. However, there are exemptions for very small shops, and the specific unit used can vary between products and retailers, sometimes making direct comparison difficult.

The phenomenon of shrinkflation has made unit pricing more important than ever. Shrinkflation occurs when manufacturers reduce the size or quantity of a product while maintaining the same selling price, effectively increasing the unit price without changing the headline figure on the shelf. High-profile UK examples include chocolate bars shrinking from 140g to 110g, packets of crisps reducing from 34.5g to 25g, and ice cream tubs dropping from 2 litres to 1.8 litres. Only by checking the unit price can you detect these hidden price increases and compare the true cost against alternatives.

How Supermarkets Use Pricing Psychology

UK supermarkets employ sophisticated pricing strategies that can mislead even careful shoppers. Multi-buy offers ("3 for £5") sometimes cost more per unit than buying a single item, especially when the single item is on a separate promotion. Larger pack sizes are not always cheaper per unit, contrary to the common assumption that buying in bulk saves money. Research by consumer groups has found that the unit price of medium-sized products is sometimes lower than both the small and large versions.

Promotional end-of-aisle displays (gondola ends) are prime retail real estate, and products placed there are not always the best value. Studies show that up to 30% of "special offer" products on end displays can be purchased cheaper elsewhere in the same store or at a competing retailer. Training yourself to check the unit price rather than the headline promotion saves significant money over time. The average UK household could save an estimated £500-£1,000 per year simply by consistently choosing the lowest unit price option in each product category.

Practical Unit Price Shopping Tips

Before your shopping trip, identify your most-purchased items and check their unit prices across different supermarkets using price comparison websites or apps. Own-brand products are almost always cheaper per unit than branded equivalents, and in blind taste tests conducted by consumer magazines, own-brand products frequently match or beat branded products on quality. The biggest savings are typically found in staples like pasta, rice, tinned goods, and cleaning products, where the formulation differences between brands are minimal.

Be cautious with "price per wash" or "price per serving" claims on packaging, as manufacturers can define serving sizes differently. A cereal brand claiming 30g servings may appear cheaper per serving than a competitor using more realistic 45g servings. Always cross-reference these claims with the unit price label on the shelf, which uses standardised measurements. Similarly, concentrated products (like washing-up liquid or squash) may offer better value per use despite a higher unit price, as you need to use less per application.