Which was the cheapest supermarket in May 2023?

Aldi was the cheapest supermarket in May, marking 12 months at the top, according to the latest monthly analysis from Which?. 

We compared the prices of a basket of 40 popular groceries in May and found that the total average cost was £68.60 at Aldi – making it the cheapest supermarket every month for the past year. 

When we looked at a trolley packed full of 131 items, Asda was the cheapest non-discounter supermarket – in fact, you could save more than £30 by doing your big shop there rather than at Waitrose. 

Read on to find out how your supermarket compares in the analysis. 

Cheapest supermarket for a basket of groceries

Every day in May, we checked the prices of 40 popular grocery items, including Heinz baked beans, milk and tea bags, at some of the UK's biggest supermarkets to see how they compared. 

The chart below shows how much our basket cost on average:

Aldi was the cheapest overall, with our shop costing £68.60, beating rival discounter Lidl by nearly £2. 

The same shop at Waitrose was £86.91 on average, making it £18.31 more expensive than Aldi.

Of the 'big four' supermarkets, Asda was the cheapest, at £76.45.

Of course, price is just one factor when you're deciding which supermarket to shop at. We also survey shoppers on product quality, customer service, store experience, online deliveries and a range of other factors, to reveal the best and worst supermarkets each year.

• Find out more: how to spend less at the supermarket

How do bigger shopping lists compare?

We also compared the cost of a larger trolley of 131 items (the original 40, plus 91 more). 

This trolley included more branded items, such as Andrex toilet paper and Cathedral City cheese. You can’t always find these items in discounter supermarkets, so we haven’t included Aldi or Lidl in this comparison.

Asda cost the least, continuing its long-running streak (which started in January 2020) as the cheapest 'traditional' supermarket. It cost £332.40, on average, for our big trolley shop, beating next-cheapest Morrisons (£334.47) by just £2.07. 

Waitrose was £31.59 more expensive than Asda, coming in at £363.99 for the same trolley of goods in May.

• Find out more: try our free My Money Health Check tool for personalised money-saving tips

How Which? compares supermarket prices

We look at the prices of hundreds of grocery items at eight major supermarkets every day throughout the year, using an independent price comparison website.

At each supermarket, we work out the average price for each item across the month; then, we add them up to get an average trolley price. To keep things fair, we include special offers, but we don’t count multibuys or loyalty scheme discounts.  

Our shopping list includes branded items such as Heinz baked beans and Dolmio sauce, as well as own-brand products like apples and lettuce. Own-brand items won’t be identical across supermarkets, but we’ve used experts to ensure everything we’ve compared is as similar as possible based on a number of factors, including quality and weight.

• Find out more: supermarket price comparison over time

What's happening to grocery prices?

The latest results from the Which? food and drink inflation tracker show supermarket prices are continuing to rise, costing on average 17.1% more in April 2023 than a year previously. That's compared to 17.2% the previous month. Cheese continued to be the fastest rising in price of all 20 categories in our research. 

The tracker, which checks more than 25,000 food and drink prices across the UK's eight biggest supermarkets, shows that own-label budget items, which are still the cheapest overall, were up 25% in April compared with the same time last year. 

This is more than standard supermarket own brands, which were up by 20.2%. Branded goods and premium own-brand ranges, meanwhile, were up 13.8% and 13.5% respectively. 

• Find out more: Which? food and drink inflation tracker

Campaign update: supermarkets must do more

Which? revealed last month that major supermarkets are failing to make their budget-range groceries available to people who have to shop in their smaller stores.

We sent a team of mystery shoppers into 123 different-sized branches of Asda, Morrisons, Sainsbury's and Tesco across the UK to assess the availability of a range of essential budget groceries. Each shopper was armed with a list of around 30 different basic budget groceries to find in each store. The results revealed shoppers who rely on Sainsbury's Local and Tesco Express stores cannot access a decent range of cheap, healthy food.

Which? believes supermarkets must do more to help their customers. Retailers should be making sure affordable basic ranges are available in all branches, including smaller convenience stores, as well as improving unit pricing (eg the price per 100g) on all products so that customers can work out the best value.

While some of the supermarkets have engaged with Which? as part of our Affordable Food for All campaign, none has committed to making any significant changes. Which? is now calling on supermarkets to act by providing the support people around the country desperately need in order to keep food on the table during the ongoing cost of living crisis.

• Do you want to see your supermarket take action to support people through the cost of living crisis? Sign our Affordable Food for All petition

Tesco Clubcard points: spend now to get maximum value

Clubcard points will be worth up to twice – rather than three times – their value when used with reward partners such as Alton Towers, Butlins and Cineworld from 14 June, so there's not long left to get the maximum value for your points. 

This will be the second time in five years Tesco has lowered the value of its Clubcard points when spent with its reward partners.

Every 150 Clubcard points earned is worth £1.50 to spend in store or online, but they are worth more if you spend them with Clubcard partners, of which there are more than 100. Currently you could turn 50p worth of points into £1.50 to use at Pizza Express or Legoland but from 14 June, 50p worth of points would only be worth £1 with reward partners.

• Find out more: Tesco to cut value of rewards points