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Which? reveals the cheapest supermarket of the year

You could save more than £20 by shopping at the cheapest supermarket

Which? reveals the cheapest supermarket of the year

Lidl was the cheapest supermarket for a trolley of groceries in 2020, exclusive Which? research reveals. 

The discount supermarket was just 34p cheaper than its nearest rival Aldi for our trolley of 45 branded and own-label groceries. 

But it was a massive £26.02 cheaper than the most expensive supermarket for an equivalent trolley of items.

Here we reveal how each of the eight biggest supermarket chains compared on price and take a look back at how grocery shopping changed in 2020. 

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The cheapest supermarkets revealed

Our trolley of groceries contained 45 popular branded and own-label products, including Hovis bread, Knorr stock cubes, eggs, cucumber and tomatoes. 

Lidl tops the table as the cheapest supermarket of 2020, closely followed by Aldi. Waitrose is the most expensive supermarket at £68.69 – a whopping £26.02 more than Lidl. 

Here’s how the supermarkets compare:

graph showing supermarket prices

Why is Lidl cheapest?

Regular readers of our ‘Cheapest supermarket of the month’ stories might be surprised to see that Lidl has been named the cheapest of 2020, given that, of the eight months in 2020 that Aldi and Lidl were included in our analysis, Aldi was cheapest six times and Lidl twice.

It all boils down to the items we’ve been able to get prices for. We look at a huge range of food and household essentials but, for our whole-year analysis, we only included things that we could get at least 100 days’ worth of data for at all eight stores.

This meant that slightly different items ended up being included from those in our monthly summaries, enabling Lidl to swing it by just 34p.

You can see the results for every month, including December 2020, on our supermarket price comparison page.

Lidl vs Waitrose: biggest price differences

We’ve unpicked the data to reveal the products with the biggest price differences between the cheapest supermarket, Lidl, and the most expensive, Waitrose.

Product Average price at Lidl Average price at Waitrose Difference between Lidl and Waitrose
Own-label cooked and peeled cold-water prawns (150g-200g) £1.99 £4.60 £2.61
Own-label chicken korma and pilau rice (400g-500g) £1.79 £3.26 £1.47
Own-label chicken drumsticks (900g-1,100g) £1.46 £2.84 £1.38
Own-label very large free-range eggs (6 pack) £1.27  £2.47 £1.20

Of course, own-brand items aren’t exactly the same at different supermarkets, but we’ve used experts to ensure that the products are as comparable as possible, based on a range of factors including weight range, quality and other industry data.

How we compare supermarket prices

We tracked the prices of 45 branded and own-label groceries listed in all eight major supermarkets for at least 100 days between 1 January and 31 December 2020. 

Using an independent pricing data provider, we calculated the average price (including special offers but not multibuys) for each item throughout the year. We added those individual averages together to give an overall price for the trolley at each shop for 2020.

Customers queuing to enter a supermarketSupermarkets during 2020

Dealing with the pandemic has caused huge upheaval for supermarkets over the past year. 

From the initial panic-buying and empty shelves to social distancing and the massive expansion of online deliveries, supermarkets have had to adapt extremely quickly. 

Retailers that already operated online were generally able to scale up their deliveries rapidly – with most doubling their capacity in just a few months. The UK’s biggest supermarket, Tesco, more than doubled delivery capacity during spring 2020 to 1.4m slots a week.

There were also new ideas. Aldi, which doesn’t have a full online delivery service, launched food parcels for home delivery. Waitrose invested in overnight picking teams, and others partnered with delivery apps, to name but a few examples.

But there were problems too. Thousands of vulnerable people struggled to get online food deliveries, while supermarket websites and apps crashed because of the unprecedented demand.

Which? has reported on how coronavirus has impacted shoppers since the pandemic first hit, and campaigned for better provision for shielding and vulnerable people when they were struggling to secure online deliveries.

To find out what’s happening now, visit our story: supermarkets coronavirus latest.

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