Aldi has been named the UK's cheapest supermarket in the latest monthly Which? supermarket price comparison.
We compared the prices of a basket of 20 products throughout July at all the major supermarkets, and found that you would have paid £23.59 on average at Aldi. It narrowly beat rival discounter Lidl by just 18p.
Buying your food at the priciest grocery retailer would have cost you £7.82 more than if you'd gone to Aldi.
But which major supermarket was cheapest for a larger trolley of 79 items in July? Read on to find out.
Each day throughout July, we checked the prices of 20 items, including own-brand products such as eggs and cucumber, and branded goods such as Chicago Town pizzas, to see how UK supermarkets compared.
Here's how much the baskets cost on average:
Aldi came out cheapest overall, at just £23.59.
Morrisons, meanwhile, was the cheapest 'Big Four' supermarket, with our basket costing £24.46. This is the first time any Big Four supermarket has been cheaper than Asda in our analysis since 2019.
At the other end of the scale, Waitrose was almost £8 pricier than Aldi, at £31.41 - that's 33% more.
Groceries with some of the biggest price differences included PG Tips pyramid tea bags, which cost £1.52 more at Waitrose than at Aldi, and own-label cantaloupe melons, which cost £1.31 more.
Of course, price is just one element to consider when you're deciding which supermarket to shop at. With this in mind, we also survey shoppers about quality, customer service, store experience, online deliveries and a range of other factors, to reveal the best and worst supermarkets annually.
We also analysed a trolley packed with 79 items (the original 20 plus 59 more).
This was made up of a wider selection of branded items, such as Amoy noodles and Lurpak butter, that aren't always available in the discounter supermarkets - so for our bigger trolley we haven't been able to include Aldi or Lidl.
Asda was the cheapest supermarket for a trolley full of goods, with the bill averaging £151.22. It was a chunky £18.28 cheaper than the most expensive supermarket, Waitrose.
Grocery prices at second-placed Sainsbury's were only 2% higher than at Asda, with our trolley costing £154.75 - that's £3.53 more - at Sainsbury's.
Food shopping with Morrisons would have set you back £159.96, or £5.21 more than if you shopped at Sainsbury's.
There was only a difference of 11p between the price of our trolley at Ocado compared with Tesco. The items were £162.74 at Ocado and £162.85 at Tesco.
We can't compare exactly the same items each month because products aren't always available at every retailer, but Asda has been the cheapest mainstream (non-discounter) supermarket for a full trolley for 17 months now, having claimed the title every month since January 2020.
We tracked the prices of 20 items at the UK's six biggest supermarkets throughout July. For our larger trolley analysis, we added a further 59 items for all supermarkets apart from Aldi and Lidl, where not all products were available.
Using an independent price comparison tool, we checked the price of each item every day throughout the month. We then calculated an average price for each item at each supermarket, and added up the individual item prices to generate an average trolley price for each store.
We included special offers but not multibuys, to keep it as fair as possible.
Our baskets and trolleys always contain a combination of branded and own-label products. 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 such as weight, quality and other industry data.
Online supermarket sales have fallen for the first time ever as coronavirus restrictions ease and people start heading back to workplaces, restaurants and physical shops.
The market share of food shopping ordered online shrank to 13.3% in the four weeks to 11 July, down from its peak of 15.4% in February 2021, according to data from market research company Kantar Worldpanel.
However, online grocery sales remain much higher than their pre-Covid level of 8.7% in February 2020. Shoppers spent £3bn more on groceries than they did during the same period in 2019, too.
Fraser McKevitt, head of retail and consumer insight at Kantar, said: 'Digital baskets have shrunk by 8% to an average of £80 per shop - the lowest since February 2020. As a result, year-on-year sales growth for online groceries has dropped for the first time ever.'
In addition, around the time of England's near-miss at World Cup glory, take-home sales of alcohol over the four weeks to mid-July fell 3% compared with the previous month. This was owing to some people opting to enjoy their newfound freedoms and watch the matches in pubs and bars, rather than at home.
Other shoppers, however, grabbed snacks and takeaway-inspired food to indulge in while watching the action unfold. Crisps and snack brands had a boost because of this, with sales growing 23% compared with two years ago, and people forked out an extra £10m on chilled and frozen pizzas over the past month.