We compared the prices of 37 popular groceries in August and found the total average cost was £65.21 at Aldi - £1.32 less than its closest rival Lidl.
When we looked at a larger trolley of 133 groceries, which didn't include the discounters, Asda was the cheapest supermarket.
Keep reading to find out how your usual supermarket compares in our analysis.
Cheapest supermarket for a basket of groceries
Our basket of 37 items included Albert Bartlett Rooster potatoes, own-brand chicken thighs and full-fat milk.
The chart shows how much our basket cost on average at the UK's eight biggest supermarkets:
Find out more:
How do bigger shopping lists compare?
We also compared the cost of a larger trolley of 133 items (the original 37, plus 96 more).
These products included a larger number of branded groceries, including Bird’s Eye frozen garden peas and Heinz cream of chicken soup. As the discounters don’t always stock big-brand products, we haven’t included Aldi or Lidl in this comparison.
The graph shows how much our larger trolley cost on average at each supermarket:
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Asda was the cheapest for our trolley of groceries, returning to its reign as the cheapest big supermarket after being beaten by Morrisons in July - the first time another supermarket earned the title since January 2020.
Our trolley cost £325.35 at Asda, comfortably beating the next cheapest supermarket Morrisons by £15.93.
Our analysis also unveiled that Waitrose was £43.69 pricier than Asda on average, with a big shop typically costing £369.04.
Find out more:How Which? compares supermarket prices
We look at the prices of hundreds of grocery items at eight major supermarkets every day throughout the month, using an independent price comparison website.
For each supermarket, we calculate the average price for each item across the month, before adding those up to get each store’s average price for our basket and trolley of products.
To keep things fair, we include special offers, but don’t incorporate multibuys or loyalty-scheme discounts into our analysis.
Our shopping list includes branded items such as Cathedral City extra mature cheddar and PG Tips tea bags, as well as own-label products such as smoked bacon rashers and little gem lettuce. As own-brand items won’t be identical across supermarkets, we’ve used experts to ensure everything we’ve compared is as similar as possible, based on several factors including quality and weight.
Find out more:What's happening to supermarket prices?
The branded product with the single largest price increase was Mr Kipling Chocolate Slices (6 pack) at Tesco. These went from £1.16 on average in the three months to the end of July 2022 to £2.66 in the same period this year - a shocking increase of £1.50, or 129%. Similarly, Mr Kipling Bakewell Cake Slices (6 pack) at Sainsbury’s went from £1.38 to £2.75, an increase of £1.37 or 99%.
Which?’s inflation tracker found that year-on-year supermarket food inflation has dipped, this time from 15.4% in the one month to the end of June to 13.8% for the one month to the end of July.
However, when comparing current prices against two years ago, prices were up 25.6% in the three months to the end of July 2023 compared with the same period in 2021.
Which? calls on supermarkets to do better
The regulator investigated 11 supermarkets and seven 'variety retailers' and found issues with unit pricing across all of them.
The findings echo Which?'s campaign which calls on supermarkets to improve unit pricing and introduce it on promotions, including loyalty prices such as Tesco's Clubcard offers.
The CMA is now asking the government to reform unit pricing legislation. It has also written to the retailers who it has found not fully complying with the law, asking them to make changes or risk enforcement action.
Which? is joining the CMA in calling on supermarkets to act now for consumers rather than waiting for the legislation to be changed.
Do you want to see your supermarket take action to support people through the cost of living crisis?source https://www.which.co.uk/news/article/which-was-the-cheapest-supermarket-in-august-2023-ag3g93o0Fjk6