Cheapest supermarket in May: Aldi vs Lidl

Aldi was the UK's cheapest supermarket in May – beating Lidl's loyalty prices by just 31p.

We compared the prices of 82 popular grocery items and found that both Aldi and Lidl (with and without loyalty prices) were cheaper than shopping at Asda, Tesco with a Clubcard or Sainsbury's with a Nectar card.

Read on to find out where was priciest, plus how the supermarkets compared on a much bigger list of 198 products.

Aldi prices beat Lidl Plus 

Throughout May, we checked the prices of 82 popular branded and own-brand groceries, including Hovis sliced bread, milk and cheese, at eight of the UK's biggest supermarkets to see how they compared.

The chart shows how much our shopping cost on average:

Aldi was the cheapest overall for our shop, beating rival discounter Lidl by just 31p if you had a Lidl Plus card, or 34p if not. 

The next cheapest was Asda, which doesn't offer loyalty prices in the same way as the others. It was 11% more than Aldi for our shopping list.

And shopping at Tesco without a loyalty card was still cheaper than shopping at Morrisons with one.

Sainsbury's was running Nectar price promotions on 12 items on our list, while Tesco had Clubcard prices on 10. Meanwhile, Morrisons had five More Card discounts on items in our basket, and Lidl had one item on our list with a loyalty discount. 

Waitrose also offers some loyalty prices to members, but there were none for items on our shopping list this month. It was the priciest supermarket again this month, averaging £184.03 – that's £48.55 (or 36%) more than Aldi.

• Find out more: cheapest supermarkets of 2025

What about a bigger shopping list? 

When we looked at a much larger selection (198 items), including more branded groceries, there were bigger savings with the loyalty schemes. 

Asda came out cheapest for this for the fifth month in a row, beating Tesco with a Clubcard by nearly £11.

Tesco with a Clubcard – which had loyalty prices on 83 of the items – was the second cheapest, followed by Sainsbury's with Nectar and Morrisons with More.

Waitrose was most expensive again, at £559.02 - 15% more than Asda. 

We couldn't include Aldi or Lidl here as they didn't stock all the branded items on our list.

You'll pay a lot more if you stock up at Morrisons, Sainsbury's or Tesco without a loyalty card.

For shoppers without a Nectar card, Sainsbury's was the second most expensive after Waitrose. 

• Interested in more than just price? Shoppers have rated product quality, customer service, online deliveries and more to reveal the best and worst supermarkets.

How much of a discount do loyalty cards give?

Based on our smaller list of products, having a loyalty card would save an average of 0.02% at Lidl, 0.6% at Morrisons, 1.37% at Tesco and 2.42% at Sainsbury's over the month.

For our longer list, which included more branded groceries and a wider selection of items with loyalty discounts, the savings were much more substantial – 1.05% at Morrisons, 6.65% at Tesco and 7.27% at Sainsbury's.

But you'd still save even more money by switching to Aldi. 

The discounts offered by loyalty cards may sound good. Butthat's  only if you can access them. Our research has found millions of people can't access loyalty promotions because they're not eligible to join supermarket member schemes due to their age, lack of address or difficulties with digital access. 

We think some supermarkets could do more to ensure certain groups of shoppers, such as those without a smartphone or those who are under 18, can access – or know how they can access – loyalty prices.

• Find out more: loyalty schemes compared

What's happening to grocery prices?

Annual grocery price inflation jumped to 4.1% in the four weeks to 18 May, according to market analysts Kantar. That's the highest level since February 2024. 

Prices are rising faster for items such as chocolate, suncare and butters and spreads. They are falling fastest for cat and dog food, and household paper products such as toilet and kitchen roll.

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

How Which? compares supermarket prices

We check the prices of hundreds of grocery items at eight major supermarkets, using an independent price comparison website. 

For each supermarket, we work out the average price of each item across the month, then add those up to get each one's average total price. 

Our shopping list comprises the country’s most popular and widely available groceries, based on extensive market analysis. 

It includes branded items such as Cathedral City cheddar and Hellmann's mayonnaise, as well as own-brand products such as potatoes and baked beans. 

Own-brand items won’t be identical across supermarkets, but we’ve ensured everything we’ve compared is as similar as possible, based on several factors, including quality and weight. 

We include special offers but not multibuy discounts. 

We are only able to take into account loyalty prices that apply to all members of a scheme (where there's one price on the shelf for shoppers with a loyalty card and another for those without). Currently, this type of two-tier pricing is used at Lidl, Morrisons, Sainsbury's, Tesco and Waitrose. 

We are unable to include discounts that are personalised to selected members, and we can’t factor in points or other rewards as these vary from customer to customer and don't always have a quantifiable monetary value.

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