A new Which? study has compared food and drink inflation across eight major UK supermarkets, including Aldi, Tesco, Waitrose and Sainsbury's, and has delivered surprising results

A new study has revealed which UK supermarket has seen the sharpest price increases.

Consumer watchdog Which? analysed 20 commonly purchased food and drink categories across eight major retailers: Aldi, Asda, Lidl, Morrisons, Ocado, Sainsbury's, Tesco and Waitrose.

The investigation examined prices over identical three-month and one-month periods on a year-on-year basis. The study factored in discounts but excluded multibuy deals or loyalty scheme promotions.

In general, annual inflation for supermarket food and drink tracked by the organisation began declining at the start of this year, reaching 4.1% in the three months ending February. This represented a fall from 4.7% in December, 5.4% last August and 4.6% in May, and was considerably lower than the 17% peak recorded in the three months to the end of April 2023.

Nevertheless, this data predates the outbreak of the Middle East crisis, with experts cautioning that it could trigger another surge in food costs.

Inflation measures the speed at which prices are increasing or decreasing rather than actual prices themselves, meaning supermarkets with the highest inflation rates may still offer better value than numerous competitors.

According to Which?'s most recent figures, Waitrose recorded the fastest-growing prices, standing at 5.3% in the three months to February, and 4.7% in February itself.

Following Waitrose, budget retailer Lidl had the second-highest inflation rate at 4.3%.

Tesco came next, at 4.3% in February, though 4.2% across the three months to that date.

Using February alone as the benchmark, Sainsbury's followed with 4%, Morrisons (3.9%), Asda (3.5%), and Ocado (3.2%).

The supermarket with the lowest rate of inflation was discount retailer Aldi, with average prices rising 2.9% in February. However, this represented a significant deceleration for the German-owned chain as its inflation stood at 3.7% in the three months to February.

Which? analysts highlighted several factors driving food price inflation. For instance, costs for fertiliser and fuel have risen, which ultimately impacts the price of numerous products on supermarket shelves.

Additionally, pandemic-related disruptions continue to have lasting effects, alongside unfavourable weather conditions in areas such as West Africa, where cocoa is predominantly cultivated. Other specialists have cautioned that conflict in Iran could drive up prices of various supermarket staples, including cereal, bread and pasta.

While Waitrose has the highest inflation rate in the Which? research, this doesn't necessarily make it the most expensive supermarket for shopping.

In fact, a separate investigation by the same consumer organisation revealed that purchasing branded products in Waitrose was actually cheaper than identical shopping in Tesco and Sainsbury's without using a Clubcard or Nectar Card.