An equivalent basket of goods was almost £22 cheaper at Aldi, when compared to the most expensive supermarket, Waitrose.

It’s the second month in a row Aldi was cheapest,  according to the data from consumer group Which?.

The basket of 43 popular items was £74.81 on average at Aldi, and £96.59 at Waitrose, a difference of £21.78.

In second place was Lidl, where the basket of items cost £77.50 on average. It was followed by Sainsbury’s, Tesco, then Asda, with prices of £85.25, £85.32, and £85.81 respectively. The consumer group analysed prices at eight of the UK’s biggest supermarkets.

It also did a separate analysis of a larger trolley of 139 items, including branded items, of just the main supermarkets and not the discount shops.

In this data, Asda was the cheapest supermarket with an average cost of £355.29 for the items. It has continued to be the cheapest of the big chain supermarkets since January 2020. Next in line was Sainsbury’s, where the same trolley would cost £358.77 on average, a difference of £3.48.

It was followed by Morrisons, at £371.86, Tesco, at £376.95, Ocado, at £382.54, and Waitrose was the most expensive with prices of £396.58 on average.

Several of the big supermarkets have launched campaigns and discounts to help with rising prices. These include a Tesco price promise from Ocado, £2 surplus food boxes from Sainsbury’s, and £3.50 ‘Magic bags’ worth £10 from Aldi.

But Which? is calling on supermarkets to do more for customers amid the cost-of-living crisis. It comes as food inflation has risen to 17.1%, a record high, adding an extra £811 to household bills.

‘Some supermarkets significantly more expensive than others’

Reena Sewraz, Which? retail editor, said: “The cost-of-living crisis has seen food and drink prices put huge pressure on household budgets.

“It is no surprise to see many people turning to discounters like Aldi, when our research shows they could save up to £22 on a typical shop.

“Our findings show that while prices are going up, some supermarkets are significantly more expensive than others. As well as choosing a supermarket that is cheap overall, you can save in other ways by swapping from branded to cheaper own-brand products, sticking to a shopping list, and resisting the temptation to pick up special offers you may not need.”