Every month, we compare how much the big supermarkets charge for a basket of groceries, including everything from bread to toothpaste.
Which? compares grocery prices at Aldi, Asda, Lidl, Morrisons, Ocado, Sainsbury’s, Tesco and Waitrose, looking at the online prices of between 100 and 200 branded and own label products, from Andrex toilet paper and Lurpak butter to Warburtons bread and Heinz baked beans.
Every month, you can see how the supermarkets compare - and discover which is cheapest.
We work out the average price of each individual food or grocery product over the month, and include special offers but not multi-buys.
We rotate the products in the basket and only compare items that are available in all the supermarkets. This means the prices aren't comparable between months or years.
To find out how your supermarket stacks up in our monthly comparison and the cheapest supermarket in our most recent analysis, Which? members can log in now.
If you're not a member, you can get instant access to all our monthly cheapest supermarket results for the last five years by joining Which?.