Smart shopping: What to skip paying full price for at the supermarket

Key Insights from the Investigation

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Which? discovered that certain grocery staples are often discounted, making full prices potentially misleading.

Branded items such as Special K and Tropicana were found to be on sale at least half the time across major supermarkets.

Consumers are advised to focus on unit pricing and track deals across different stores to maximize savings.

The Impact of Supermarket Promotions

We all know that your choice of supermarket makes a difference to the price of your groceries. Each month, the team at Which? reveal the cheapest retailers, with Aldi regularly taking the crown and Lidl following not far behind. However, the findings of their latest investigation suggest that it’s not just where you shop that matters, but also when.

The consumer champions delved into supermarket promotional strategies and found that some of the UK’s favourite branded products are on offer so often that shoppers should never be paying full price for them.

Tracking Prices Across Major Supermarkets

Which? kept track of the prices of thousands of popular groceries from March 2025 to March 2026 at Asda, Morrisons, Ocado, Sainsbury’s, Tesco, and Waitrose. While doing so, they claim to have identified ‘clear patterns’ of rotating three-to-four-week discount cycles. This means shoppers could be paying ‘over the odds’ for popular items when they are not on promotion, as they are most likely on offer somewhere else.

Several grocery staples, such as Kellogg’s Special K cereal, Tropicana Orange Juice, and Fox’s Chocolate Biscuits, were found to be on offer at one major supermarket or another every single day of the year. The experts at Which? said this discovery was particularly ‘alarming’, explaining: ‘The sheer amount of time individual supermarkets kept these items on promotion highlights why shoppers should take the listed “full price” with a pinch of salt.’

Examples of Frequent Discounts

According to the findings, a 440g box of Special K consistently sat at a full price of £3.30 to £3.50. But if you were to shop around, you could buy it for £2.85 or less somewhere else every single day of the year. Ocado had the cereal on offer most frequently, as they sold it on promotion 51% of the time. This was closely followed by Tesco at 50%, and Waitrose at 48%.

Discounts on Special K were less frequent at Asda and Morrisons, but the cereal was still discounted in these stores 29% of the time, when the price dropped as low as £2.63.

Tropicana Orange Juice (1.5L), which costs between £4.28 and £4.75 at full price, was also discounted to £3.50 or less 99% of the year. Fox’s Chocolatey Milk Chocolate Biscuit Rounds (130g) were on offer for 99% of the year, costing £1.75 or less, instead of £2 to £2.75. Other examples included Nestlé Shredded Wheat Cereal (625g), which was available at a discounted price of £3 or less 97% of the time. Onken Set Natural Yogurt (450g) was also consistently marked down throughout the year, as were Kettle Chips Lightly Salted Crisps (130g).

Extreme Price Fluctuations

The investigation also uncovered ‘extreme’ price swings on branded items in supermarkets. One of the most notable was a four-pack of Light & Free Peach Passion Fruit Greek Style Yogurt. The price is said to have fluctuated by 190%, costing £1 at Ocado at its lowest and £2.90 at Waitrose at the highest. Asda had the single biggest price hike within the same store, on Amaara plain poppadoms (200g). These cost just 48p at their lowest, but jumped to £1.50 at a different point in the year.

Despite this, Asda currently remains the cheapest supermarket for buying branded groceries, according to Which’s monthly price monitor.

Advice for Shoppers

Decode the Shelf Labels: Supermarkets hide promotional end dates in plain sight. Tesco reverses the end date on shelf tags, Sainsbury’s shows the deal’s start date, and Waitrose utilises a four-digit month/year code.
Shop Different Aisles: Check world food aisles for cheaper bulk grains/spices, or the baking aisle for larger, more economical packs of dried fruit and nuts.
Audit Unit Pricing: Always judge value by the price per 100g or 100ml rather than the flash sale banner.
Avoid Convenience Outlets: Shopping at smaller convenience stores can incur a premium markup of up to 21% compared to a brand’s larger supermarkets, according to research Which? did in 2024.
Utilise Price Trackers: Consistently tracking shopping baskets shows that Asda remains the cheapest baseline for branded items, while Sainsbury’s and Tesco (without loyalty cards) rank as the most expensive.

Reena Sewraz, Which? retail editor, said: ‘Supermarkets are using dizzying pricing cycles to create a false sense of urgency, but our investigation blows the lid off these endless promotions. When items like Tropicana and Special K are on sale nearly every single day of the year, the “full price” becomes entirely meaningless.’

She adds: ‘To avoid being ripped off, shoppers need to ignore the flashy promotions and look closely at the unit pricing on the shelf edge – the price per 100g or 100ml – to see what they are actually getting for their money. If you are loyal to a certain branded item, it could be worth tracking prices across multiple stores and stocking up when you see a good deal.’

Groceries You Should Never Buy at Full Price

Kellogg’s Special K Original Cereal (440g)

Full price: £3.30 to £3.50

Promotional price: £2.85 or less

Investigation findings: On a deal somewhere every single day. On promotion 5% of the year at Ocado and 50% at Tesco.
Tropicana Orange Juice Original (1.5L)

Full price: £4.28 to £4.75

Promotional price: £3.50 or less

Investigation findings: On promotion every single day of the year at one of the tracked retailers. Available at £3.50 or less 99% of the time in at least one of the major supermarkets.
Fox’s Chocolatey Milk Chocolate Biscuit Rounds (130g)

Full price: £2 to £2.75

Promotional price: £1.75 or less

Investigation findings: On promotion every single day of the year at one of the tracked retailers. Available at £1.75 or less, 99% of the year at least one of the major supermarkets.
Nestlé Shredded Wheat Cereal (625g)

Full price: £3.50 to £3.95

Promotional price: £3 or less

Investigation findings: On promotion at £3 or less 97% of the time.
Onken Set Natural Yogurt (450g)

Full price: £1.75 to £2.10

Promotional price: £1.50 or less

Investigation findings: On promotion every single day of the year at one of the tracked retailers. Was £1.50 or less 99% of the time at one major supermarket or another.
Kettle Chips Lightly Salted Crisps (130g)

Full price: £2.40 to £2.65

Promotional price: £1.65 or less

Investigation findings: On promotion at £1.65 or less every single day of the year at one of the tracked retailers.