Asda was the cheapest major online supermarket in May, according to new Which? analysis.
It’s the third month in a row that Asda has topped our table for the cheapest online supermarket.
We compared prices across 178 grocery items throughout last month and found that, on average, shoppers would have paid £279.54 at Asda – £14.64 less than at Morrisons, its nearest rival price-wise.
But which of the supermarkets was the most expensive? And what about discounters Aldi and Lidl? Here, we compare supermarket prices across all the big names and explain how coronavirus has changed the way we conduct our pricing research.
How do supermarket prices compare?
We checked the prices of 178 items, from coffee to Kleenex, throughout May to see how UK supermarkets compared.
We looked at a combination of branded and own-label goods, which have been selected by experts to be as comparable as possible.
We can’t compare exactly the same items each month because products aren’t always available at every retailer, but Asda was also the cheapest major online supermarket when we checked in April.
- Find out more: supermarkets coronavirus latest
What about Aldi and Lidl?
We weren’t able to get a full range of prices at the two discounters this month.
Unlike the other major supermarkets, Aldi and Lidl don’t list all of their prices online and, due to coronavirus, it’s not possible for us to send fieldworkers to stores to check a full trolley-worth of grocery prices.
We did manage to get a limited number of prices, which meant we could compare a small basket of eight grocery items (including milk and cucumber) across all eight of the UK’s biggest supermarkets, including Aldi and Lidl.
Lidl was the cheapest supermarket overall, at £9.01 for our basket – beating Aldi by just 12p. The cheapest of the non-discounters was Asda, at £10.74, while the most expensive supermarket for this limited basket of groceries was Waitrose at £14.79.
In March, when we were able to include a much larger selection of products from the discounters, Aldi emerged as the cheapest supermarket.
- Find out more: advice for vulnerable households on grocery deliveries
How Which? compares supermarket prices
We tracked the prices of 178 items at the UK’s six biggest supermarkets throughout May.
On our shopping list were own-brand items such as pasta, eggs, lettuce and milk, as well as branded items such as Kenco Millicano coffee, Oxo stock cubes and Patak’s curry paste pots.
Using data from an independent price comparison website, we calculated the average price (including special offers but not multibuys) for each item throughout the month. We added those individual averages together to give an overall price for the trolley at each shop for the month.
- Find out more: how to store food safely during the coronavirus pandemic
How our research has changed to include Aldi and Lidl
Which? has been analysing supermarket prices for years, but we changed our methodology earlier this year to include Aldi and Lidl for the first time.
Why? We used to only include branded products in our trolley. This had the advantage of ensuring that we were strictly comparing like with like. However, the downside was that, as Aldi and Lidl primarily sell own-label items with just a small supplementary range of branded goods, they couldn’t be included.
Many Which? members told us that they would find it helpful to be able to see how the discounters compared with the mainstream supermarkets. We listened to that feedback and have added own-label items to our trolley to enable us to widen the net of retailers we include.
We used experts to ensure that the products are as comparable as possible, based on a range of factors including weight, quality and other industry data.
However, due to the UK-wide lockdown, we were unable to get a full range of prices at the two discounters in April and May.
- Find out more: how to stay safe at the supermarket during coronavirus
Should you choose a supermarket purely based on price?
For many people, price isn’t everything; customer service and the overall experience of being in the store can also make a big difference.
And with grocery shopping recently affected in unprecedented ways due to the coronavirus pandemic, extra factors will probably be influencing your choice of supermarket: proximity if you’re able to get to the shops, or the availability of online delivery slots if not (see below for more info on this).
If you’re lucky enough to have a choice right now, you might be interested to see which retailers Which? members have voted as the best online and in-store supermarkets.
- Find out more: how to shop safely in store
Supermarket reactions to coronavirus
The past few months have been a whirlwind for supermarkets, with panic buying, lockdown and social distancing all presenting unprecedented challenges for the sector and shoppers alike. Which? has been working hard to provide advice about what’s going on with supermarket shopping. If you want to know more, read the following articles:
- Supermarkets coronavirus latest, including opening hours for key workers and online delivery slots
- How to get food delivered to vulnerable households
- Which? calls for urgent government action to get food to clinically vulnerable people
- Safest ways to pay volunteers for your shopping
- How to stay safe in supermarkets
- Analysis: the truth about grocery stockpiling