The consumer champion compared the average price of a shop consisting of popular groceries at eight of the UK’s biggest supermarkets.
The cheapest supermarket for a shopping list of 59 items was Aldi, where the groceries cost £102.68 on average across the month.
Fellow discounter Lidl was just behind Aldi in September, costing £103.86 on average, £1.18 more than Aldi.
The full results
The table below shows the cost of the shop at each of the main supermarkets.
| Retailer | Average price |
| Aldi | £102.68 |
| Lidl | £103.86 |
| Asda | £112.19 |
| Tesco (with Clubcard) | £112.96 |
| Tesco (without Clubcard) | £113.35 |
| Sainsbury’s (with Nectar) | £113.79 |
| Morrisons | £119.18 |
| Sainsbury’s (without Nectar) | £119.19 |
| Ocado | £125.16 |
| Waitrose | £130.37 |
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As the table shows, Waitrose was the most expensive supermarket this month, totalling £130.37 on average. This equates to a difference of £27.69 compared to Aldi, which is 27% more.
The list of 59 items included both branded and own-brand items, such as Birds Eye Peas, Hovis bread, milk and butter.
Tesco Clubcard members would have paid £112.96 on average. Without a Clubcard, the Tesco shop cost £113.35.
For those using a Sainsbury’s Nectar card, September’s shopping list of items averaged £113.79, which is £11.11 more than at Aldi and still higher than the prices at Lidl (£103.86), Asda (£112.19) and Tesco (£112.96/£113.35). Without a Nectar card, the same items at Sainsbury’s cost £119.19.
While Lidl, Morrisons and Waitrose also operate two-tier pricing for members and non-members, their schemes are currently smaller-scale and Which? said that no items on its shopping list were available at a lower price to members of these schemes.
Which? compares supermarket prices every month. This month, it compared 59 items but the data is taken from a longer list of about 200 items, based on availability across supermarkets that month. The list is made up of some of the UK’s most popular groceries, based on industry data on sales value and availability. It includes special offers and loyalty discounts where applicable, but not multi-buys.
Because the main list of around 200 groceries remains unchanged from month to month (other than being refreshed occasionally to reflect consumer shopping habits), Which? never shares the full list of products with retailers as it wants to avoid any attempt to skew the results.
Ele Clark, Which?’s retail editor, said: “Our latest monthly analysis once again sees Aldi crowned as the UK’s cheapest supermarket.
“Given the ongoing strain of high food prices on household budgets, it’s understandable that many people are choosing discounters to cut costs. By switching supermarkets, consumers could save 21%, highlighting the advantages of shopping around.”
