We compared the prices of 100 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 for a much bigger list of 210 products.
Aldi prices beat Lidl Plus
Throughout January, we checked the prices of 100 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:
Find out more:What about a bigger shopping list?
When we looked at a much larger selection (210 items), including more branded groceries, there were bigger savings with the loyalty schemes.
Members of Asda's Rewards scheme also would have earned 95p cashback on average on products with loyalty promotions. We haven't factored this into our main analysis because loyalty members don't receive a discount on the day, and cashback is only redeemable at Asda within a limited period (up to nine months) and in increments of £1.
Tesco Clubcard – which had loyalty prices on 87 of the items – was second cheapest, followed by Morrisons More and Sainsbury's Nectar.
Waitrose was priciest again, at £592.34 - 14% more than Asda.
We couldn't include Aldi or Lidl here as they didn't stock all the branded items on our list.
For shoppers without a Nectar card, Sainsbury's was second-most expensive after Waitrose.
Interested in more than just price?How much 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, 0.7% at Morrisons, 2.57% at Tesco and 4.38% at Sainsbury's over the month.
For our longer list, which included more branded groceries and a bigger selection of items with loyalty discounts, the savings were much more substantial – 1.9% at Morrisons, 7.04% at Sainsbury's and 6.07% at Tesco.
But you'd save even more money by switching to Aldi.
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:What's happening to grocery prices?
Annual grocery price inflation slowed to 3.3% in the four weeks to 26 January 2025, according to market analyst Kantar.
Prices are rising fastest for items such as chocolate, chilled smoothies and juices and butters and spreads. They are falling fastest for some cooking sauces, household paper products (such as toilet roll and kitchen roll) and cat food.
Find out more:Asda back on top form
Asda's return to the top spot for our longer shopping list comes just days after it announced it was dropping its Aldi and Lidl price match scheme.
The supermarket, which saw sales fall in the run-up to Christmas, has instead revived its Rollback pricing - claiming to have slashed the prices of more than 4,000 products in-store and online by an average of 25%.
It may be too early for many of these price cuts to have made a huge difference to our cheapest supermarket rankings this time - but it will be interesting to see what the results show next month.
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 store’s average 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:source https://www.which.co.uk/news/article/cheapest-supermarket-in-january-can-aldi-beat-lidls-loyalty-prices-ar45v1R4rSZH