Which was the cheapest supermarket in September 2022?

Aldi was the cheapest supermarket in September, according to the latest monthly analysis from Which?. 

We compared the prices in a basket of 48 popular grocery items in September. The pricing analysis found that shoppers would have paid £75.61 for the shop at Aldi. 

In the wider analysis – including 149 items across the six 'traditional' supermarkets – we found that you could save £41.13 by shopping at Asda rather than Waitrose. 

Read on to find out how your supermarket compares in the analysis. 

Cheapest supermarket for a basket of groceries

Every day in September, we checked the price of 48 popular groceries, including Heinz baked beans, milk and tea bags, at the UK's biggest supermarkets to see how they compare. 

The table below shows how much our basket cost on average:

Aldi was the cheapest overall, with our shop costing £75.61, on average, beating rival discounter Lidl by £1.84. 

The same shop at Waitrose was £99.40, on average, making it £23.79 more expensive than Aldi.

Of the 'big four' supermarkets, Asda was the cheapest at £84.87.

Of course, price is just one factor when you're deciding which supermarket to shop at. We also survey shoppers on their experiences in terms of product quality, customer service, store experience, online deliveries and a range of other factors, to reveal the best and worst supermarkets each year.

• Find out more: read our guide on how to spend less at the supermarket and watch the video below for more tips from our experts

How do bigger shopping lists compare?

We also compared the cost of a larger trolley of 149 items (the original 48, plus 101 more). 

This trolley included a larger number of branded items, such as Andrex toilet paper and Cathedral City cheese. You can’t always find these items in discounter supermarkets, so we haven’t included Aldi or Lidl in this comparison.

Asda cost the least with this trolley of groceries, continuing its streak, which started in January 2020, as the cheapest traditional supermarket. It cost £343.38, on average, for our big trolley shop, beating the next cheapest, Sainsbury's (£353.15), by £9.77.

Waitrose was a whopping £41.13 more expensive than Asda, coming in at £384.51, on average, for the same trolley of goods. 

• Find out more: If you need help managing your finances during the cost of living crisis, try our free My Money Health Check tool for personalised money-saving tips.

How Which? compares supermarket prices

We look at the prices of hundreds of grocery items at eight major supermarkets every day throughout the year, using an independent price comparison website.

For each supermarket, we work out the average price for each item across the month, then we add those up to get each store’s average trolley price. To keep things fair, we include special offers, but we don’t count multibuys or loyalty scheme discounts.  

Our shopping list includes branded items such as Heinz baked beans and Dolmio sauce, as well as own-brand products such as apples and lettuce. Own-brand items won’t be identical across supermarkets, but we’ve used experts to ensure everything we’ve compared is as similar as possible, based on a number of factors including quality and weight.

• Find out more: supermarket price comparison over time

Supermarkets: inflation latest

Grocery price inflation was 12.4% in the four weeks to 4 September, according to market analysts Kantar. That's again the highest level since Kantar started measuring it in 2008. 

Fraser McKevitt, Kantar's head of retail and consumer insight, said: 'It seems there’s no end in sight to grocery inflation, as the rate at which food and drink prices are increasing continues to accelerate. Now standing at 12.4% for August, the latest figure means that the average annual grocery bill will go from £4,610 to £5,181 if consumers don’t make changes to what they buy and how they shop to cut costs. That’s an extra £571 a year. Categories like milk, butter and dog food are jumping up especially quickly, at 31%, 25% and 29% respectively.'

There was also a landmark moment this month when Aldi overtook Morrisons in market share - the traditional 'Big Four' supermarkets (Tesco, Sainsbury's, Asda and Morrisons) are seemingly no more. It shows how shoppers are switching supermarkets to manage their budgets as the cost of living crisis continues. 

September also saw Which? launch its cost of living campaign with key calls on supermarkets to do more.

• Find out more: what supermarkets are doing to help with the cost of living