The Missing Grams Ledger: 24 UK Grocery Staples, 12 Months, and the Quiet Cost of What Vanished
Photo: Alexander P Kapp, CC BY-SA 2.0, via Wikimedia Commons
Shrinkflation rarely announces itself. It doesn't need to. The packet still says 'family size', the shelf edge still carries a reassuring price, and the only number that moves is the one most of us ignore: net weight. Between November 2025 and November 2026 we tracked 24 everyday grocery staples across four UK supermarkets — own-label and branded — and put the missing grams on a price tag. Some packs lost a tenth of their contents. A few held firm. Two actually got bigger. The pattern is what matters, not any single product.
How we ran the weigh-in
We bought the same or nearest-equivalent lines every four weeks: cereal, cheddar, crisps, tea bags, washing powder, chocolate, biscuits, coffee, pasta, rice, butter, yoghurt, orange juice, bread, sausages, frozen peas, tinned tomatoes, shampoo, toilet roll, dry dog food, olive spread, baked beans, granola bars and frozen chips. For each one we photographed the net weight, recorded the regular shelf-edge price rather than a short-lived promotion, and worked out the unit price per 100g, 100ml, per wash or per sheet.
The comparison was like-for-like wherever possible. If a pack changed size, we did not compare it with a different tier or a bulk pack. If a brand disappeared, we swapped in the closest equivalent and noted the switch. This is a small sample, not a national index. But it is the kind of sample a real shopper builds up without realising: the same basket, month after month, with one quiet detail changing in the background.
The biggest disappearances
Of the 24 lines, 17 ended the year lighter than they started. Five stayed the same weight. Two got bigger — frozen peas and own-label pasta, both in competitive categories where supermarkets were pushing volume. The average missing weight across the 17 shrinking lines was 7.4%. The average shelf-price increase across those same lines was 6.1%. Put those together and the unit price rose by an average of 14.3%. That is the bit that stings: shoppers were not just paying more per pack, they were paying more per gram on top.
Here are six examples from the ledger, with the missing grams priced at the new unit price:
| Product | Old weight | New weight | Shelf price then to now | Cost of missing grams |
|---|---|---|---|---|
| Breakfast cereal | 500g | 450g | £2.40 to £2.55 | 28p |
| Mature cheddar | 400g | 350g | £3.20 to £3.40 | 49p |
| Crisps multipack | 150g | 132g | £1.75 to £1.85 | 25p |
| Tea bags | 250g | 225g | £2.00 to £2.15 | 24p |
| Washing powder | 2.6kg | 2.34kg | £7.00 to £7.50 | 83p |
| Milk chocolate | 200g | 180g | £2.00 to £2.20 | 24p |
Those numbers are not huge on their own. That is the point. A 24p shortfall on chocolate does not trigger a complaint. A 49p shortfall on cheese hides inside a pack that still looks like a decent chunk of cheddar. But add a few of these to a weekly shop and the annual cost becomes real. A household buying 10 of these shrinking lines each month would lose roughly £36 to £60 a year in missing grams, depending on the mix.
The unit-price truth
Shrinkflation is easier to spot when the pack price stays flat. If a 500g box becomes 450g and the price does not move, the unit price rises by 11.1%. If the price also creeps up by 5%, the unit price jumps by about 16.7%. That is why the shelf-edge price is such a poor guide on its own. It tells you what you are handing over, not what you are getting.
The supermarket defence is usually fair on one point: recipes, ingredients and packaging costs do change. Not every smaller pack is a con. Some lines were reformulated, and we did not audit ingredient lists in detail. But the shopper is still left doing the same calculation at the shelf. The retailer knows the unit price is printed. It is just not the number most of us read when we are moving quickly.
We also found a split between categories. Store-cupboard staples such as pasta and rice were more likely to hold their weight or grow, because the competition is fierce and own-label packs are easy to compare. The quieter downsizing happened in branded cereal, chocolate, tea and household consumables, where the pack is familiar and the shopper is less likely to check the small print every week.
The lines that held — or grew
Not everything shrank. Frozen peas, own-label pasta and tinned tomatoes held their weight or increased it in our sample. In a couple of cases the unit price actually fell. That matters because it shows shrinkflation is not a law of nature. It is a commercial choice, and it is more likely in categories where shoppers are loyal to a format or a brand.
We also saw why comparing pack sizes matters more than comparing pack prices. One shrunken branded cereal at 450g and £2.55 worked out at 56.7p per 100g. A larger own-label box at 500g and £2.20 worked out at 44p per 100g. The branded box still looked like the familiar choice. The own-label box was 22% cheaper per 100g. Neither was automatically 'better', but the unit price made the decision visible.
The shelf-side method: three checks before you buy
1. Find the unit price, not the pack price. UK shelf labels normally show a price per 100g, per 100ml, per kg or per litre. If the label is missing it, use your phone calculator: price divided by weight in grams, then multiplied by 100. That single number cuts through most of the fog.
2. Compare across sizes, not just brands. The bigger pack is not always better value, and the smaller pack is not always worse. A 450g box at £2.55 is not the same product as a 500g box at £2.20 once you do the maths. Check two sizes of the same line before you pick one up.
3. Use the right unit for non-food. Washing powder is better judged per wash, toilet roll per 100 sheets, tea bags per bag. A pack that looks the same size can hide fewer washes or fewer sheets. If the pack says '40 washes' and the new one says '36 washes', that is a 10% cut even if the box looks identical.
A fourth habit helps: keep a note of the net weights of your regulars. It does not need to be a spreadsheet. A photo of the packet on your phone is enough. When the packaging changes, or the weight quietly drops, you have a baseline to compare against. Treat 'new look' or 'improved recipe' as a prompt to check the unit price, not a reason to trust it.
What this means at the till
The honest conclusion is not that every supermarket is out to trick you. It is that the shelf is designed for speed, and shrinkflation thrives on speed. The missing grams are real money, but they are not usually big enough to notice in a single shop. They become visible when you compare unit prices and keep half an eye on the weights of the things you buy most.
Our 24-line ledger found 17 quiet downsizes in 12 months. That is not a scandal. It is a habit. The practical response is a habit too: read the unit price, check the net weight, and compare the pack in your hand with the one next to it. BestBuyGet UK's view is simple — a deal is only a deal if you know what you are getting per gram, per wash or per sheet. The rest is just packaging.
