Supermarkup – Which? reveals the grocery products that you could be paying too much for

Shoppers who regularly buy Persil laundry detergent, Andrex toilet paper and Kenco Millicano coffee could be overpaying by up to £3 per item as a new Which? investigation reveals the shocking price differences between supermarkets on popular products.

The consumer champion analysed thousands of prices across six months at major UK supermarkets – Aldi, Asda, Lidl, Morrisons, Ocado, Sainsbury’s, Tesco and Waitrose – including both own label and branded items. 

Which? experts found big variations in the price of the same branded groceries at different supermarkets. The pricing analysis also showed how prices on some items fluctuate dramatically even at the same supermarket chain – exposing one of the most common tricks of supermarket pricing. 

Persil non-biological washing liquid had the biggest price difference of any branded product in the investigation, and was on average £2.98 more at Morrisons than at Lidl. 

Andrex Supreme Quilts toilet tissue had the second biggest average price difference, costing £2.60 more at Waitrose than at Morrisons, which offered the cheapest average price.

Waitrose and Ocado were the most expensive on average for Kenco Millicano coffee, which was £2.06 less on average at Aldi. Waitrose also charged the most for Hellmann’s Real Squeezy Mayonnaise, which was £1.87 less at Sainsbury’s, and PG Tips Pyramid Tea Bags, which were £1.87 less at Asda.

Out of all the products Which? included in its pricing analysis, Persil non-bio also had the biggest price variation within the same supermarket chain – alternating fairly regularly between £5 and £10 at Morrisons across the six month period. Which? found the price also varied at several other supermarkets – by as much as £4 at Tesco, £3.50 at Asda and £3 at Ocado.  

Other products that varied significantly at the same retailer included PG Tips Pyramid tea bags, which fluctuated by £2.77 at Ocado, and Twinings English Breakfast and Twinings Every Day Tea Bags, which both changed by £2.65 at Sainsbury’s. Andrex Supreme Quilts toilet tissue paper fluctuated by £2.65 at Waitrose.

By dropping a price on a popular item and advertising it as a discount before raising it for a short while and then dropping it again, supermarkets give the illusion that shoppers are making a saving. In reality, shoppers buying at the higher price are paying more than they should to compensate for the times the price is lower.

When it came to non-branded items, Which? found price differences that were even more stark. Own-brand prawns were on average £3.28 more at Ocado and Waitrose than at Aldi – the biggest price difference across supermarkets of any product in Which?’s investigation. 

There were also yawning gaps between the supermarkets on prices for own-label salmon fillets which varied by £2.26 on average between Waitrose and Aldi. 

Olive oil varied by £1.81 between Ocado and Waitrose where the price was the same, and Aldi. Beef sirloin steak was around £1.72 more at Ocado than Lidl and Aldi where the price was also the same. Similarly an equivalent ready meal of chicken korma with pilau rice was £1.51 more at Ocado than at Aldi and Lidl, where the price was also the same.

While Which? used experts to ensure that the own-brand products were as comparable as possible based on a range of factors including weight, quality and other industry data, they will inevitably differ in terms of quality, freshness, and taste across different supermarkets. 

Quality, range, customer service, store layout and convenience are also important factors, and may lead some consumers to choose a more expensive supermarket for their weekly shop. 

Despite often being the most expensive supermarket, Waitrose topped Which?’s annual supermarket survey. Customers gave the high-end store full marks for the appearance of its stores and range of products although perhaps unsurprisingly it did not do well for value for money. 

Meanwhile, despite low scores on product range and store appearance, Aldi was also rated highly in Which?’s survey by shoppers who value low prices.

For shoppers watching their purse strings, Which? recommends keeping an eye out for fluctuating prices and dodgy special offers. 

Natalie Hitchins, Head of Home Products and Services at Which?, said:

“While prices will inevitably vary between different supermarkets, shoppers might be shocked to see that they could be overpaying by such significant margins for exactly the same products.

“Most supermarkets use some sneaky pricing tactics from time to time, so pay attention to the prices of your favourite products – and don’t assume you’re getting a good deal just because the item is on offer.”


  • Which? analysed thousands of grocery prices at eight major UK supermarkets – Aldi, Asda, Lidl, Morrisons, Sainsbury’s, Tesco, Waitrose and Ocado – including both own label and branded items.
  • For the overall price comparison, Which? looked at a trolley of 87 grocery items that were available in each supermarket for at least 50 days between the beginning of March and the end of August 2020.
  • Which? experts used weight, quality and other industry data to ensure own-label products were as comparable as possible. 
  • Groceries are one of the biggest household expenses. In fact, according to the Office for National Statistics, we spend an average of £61.90 per week on food and non-alcoholic drinks; that’s 11% of our household spend.
  • The economic uncertainty brought about by Covid-19 has led to a renewed focus on price. Indeed, supermarkets are currently waging price wars in various different ways, both by trying to cut basic everyday prices and also through a range of promotions, loyalty-related discounts and price-matching.

Branded groceries with big price differences

Supermarket with the highest average price Supermarket with the lowest average price Biggest average difference
Persil Non Biological Washing Liquid (1.33l) Morrisons Lidl £2.98
Andrex Supreme Quilts Toilet Tissue (16 rolls) Waitrose Morrisons £2.60
Kenco Millicano Coffee (100g) Waitrose and Ocado Aldi £2.06
Hellmann’s Real Squeezy Mayonnaise (705-750ml) Waitrose Sainsbury’s £1.87
PG Tips Pyramid Tea Bags (240 bags) Waitrose Asda £1.87

The own-brand groceries with big price differences

Supermarket with the highest average price Supermarket with the lowest average price Biggest average difference
Cooked and peeled cold water prawns (150g-200g) Ocado (Waitrose own label) and Waitrose Aldi £3.28
Fresh salmon fillets (220g-340g) Waitrose Aldi £2.26
Olive oil (1,000ml) Ocado (Waitrose own label) and Waitrose Aldi £1.81
Beef sirloin steak (173-275g) Ocado (Waitrose own label) Aldi and Lidl £1.72
Chicken korma and pilau rice (400g-500g) Ocado (Waitrose own label) Aldi and Lidl £1.51

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