Supermarket price promises under the microscopeAsda, Sainsbury's or Tesco - which is cheapest?

23 October 2013

A new Which? investigation has revealed significant differences between supermarket price-matching schemes - making it hard to tell which is the cheapest supermarket overall.

We analysed shopping trips made to Asda, Sainsbury’s and Tesco, which all run price-match schemes. In the majority of cases the supermarket visited claimed to be cheaper than its rivals. 

However, all three schemes use different methods to measure which is cheapest, and they don’t always include the same items.

Find out which stores Which? members rate as the best and worst supermarkets.

Rising food prices a worry for many

Which? executive director, Richard Lloyd, said:

'Supermarket price-matching schemes can save you money but we believe they should be taken with a pinch of salt because they are difficult to compare.

'At a time when consumers are feeling a squeeze on their household incomes, we want all the supermarkets to do everything they can to help consumers find the best deal.'

Rising food prices are consistently one of the top financial worries for consumers. Latest Which? research shows only three in 10 consumers trust supermarkets to charge a fair price for food.

Seven in 10 (71%) shoppers say price is one of the most important factors when shopping for food, meaning supermarket price-matching schemes can be an attractive incentive. However, for the 59 shopping trips we analysed, the vouchers our shoppers received offered an average discount of just £1.45.

How we researched supermarket price matching

We analysed 19 receipts for shopping trips made at Asda, which was cheapest for 17 of these, according to its Price Guarantee scheme.

Of the 20 Sainsbury's shopping trips we examined that were eligible for its Brand Match scheme, Sainsbury’s was cheaper than Asda and Tesco for 10 of these visits and was joint-cheapest for another two, according to its calculations.

For Tesco, we also looked at 20 shopping trips that were eligible for its Price Promise. Tesco was cheaper than Asda and Sainsbury’s for 10 of these, according to its calculations.

We also looked at the terms and conditions of each price match, including how quickly vouchers expire. Sainsbury’s and Ocado vouchers expire quickest - in 14 days - compared with 28 days for Asda and Tesco.

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