Asda was the cheapest supermarket for our basket of branded products during 2016, comfortably ahead of second-placed Morrisons.
The basket of 80 items – made up of popular items such as Dolmio sauce, Nescafe Gold Blend coffee and Warburtons bread – cost £154.14 on average at Asda, compared to £160.19 at Morrisons.
Waitrose was the most expensive supermarket – the same items cost over £18 more there than at Asda.
Which? magazine editor Richard Headland said: ‘With increasing concern over rising food prices, our research shows that some supermarkets are consistently cheaper than others. It could be worth switching supermarkets, or shopping around, if you want to trim your shopping bill.’
Take a look at our supermarkets review to discover which supermarkets are rated best and worst for price, customer service, product range and more, based on our survey of thousands of shoppers.
How we compare supermarket prices
To compare supermarket prices across the year, we started with a list of more than 100 popular products, which were likely to be sold in the six supermarkets covered by the comparison.
Using data from the independent shopping website MySupermarket, we calculated the average price (including discounts, but not multibuys) for each item across the whole of 2016. We added those average prices up to get the cost of the basket.
If a product wasn’t sold in one of the six supermarkets during the year, it was removed from the basket altogether to ensure a fair comparison.
While this data covers the whole of 2016, we also look at the cost of the basket each month, using the same method, and publish the results on Which.co.uk.
Asda was consistently dominant all year, coming out on top in 11 out of 12 months in 2016. February was the only exception, when Morrisons bumped it into second place.
M&S comes out on top for Best Buys
When it came to picking up Best Buys for own-brand products, Marks & Spencer was the clear best supermarket in 2016. Overall, it won seven Best Buys.
In total, eight supermarkets won Best Buys for their own-brand products in 2016. You can find out which Best Buy products to buy at each supermarket by reading their full reviews: