How we score
Same price, less product. We do the maths, and we show our working. The Value Erosion Score is one number from 0 to 100 that tells you how much value a product has quietly lost. Higher is worse. We never show the score without the figures it came from.
Two ways a pack gets worse
A product can shortchange you on quantity, on quality, or on both at once. We track each one and then combine them.
The pack gets smaller while the price holds. You pay the same money for less product, so the price per 100g, per 100ml or per item quietly climbs.
The recipe gets cheaper. The declared percentage of the named hero ingredient, the QUID figure on the label, drops. Less of the good stuff for the same money.
The quantity maths
We take the earliest and the latest pack we have on record and compare the unit price, which is the price per 100g, per 100ml, or per single item. The rise in that unit price is the hidden price rise you are really paying.
Worked example
It was £2.00 for 200g, which is £1.00 per 100g. It is now £2.00 for 170g, which is £1.18 per 100g.
The shelf price never moved, but the unit price went up. That is a hidden 18% price rise for the same thing.
When a price is not on record, we fall back to the pure size reduction and say so plainly. That is the hidden rise you pay if the shelf price held, which is the documented reality of most shrinkflation: same price, less product.
The quality maths
Pre-packed food in the UK has to declare the percentage of a named ingredient when it is emphasised on the label. That is the QUID figure, short for Quantitative Ingredient Declaration. We compare the earliest and latest declared percentage of the hero ingredient.
Worked example
Declared pork fell from 97% to 90% of the recipe.
That is about 7% less of the ingredient you are paying for, with the packet looking much the same.
Blending the two
When a product has lost value on both pillars, we combine the losses the way they actually stack up rather than just adding them. If a pack costs 10% more per gram and also has 10% less of the hero ingredient, the total value lost is a little under 20%, because the second loss applies to what is already a worse pack.
The formula
loss = 1 minus (1 minus quantity loss) times (1 minus quality loss)
The result, as a percentage from 0 to 100, is the Value Erosion Score.
When only one pillar has data, we score on that pillar alone and label it clearly as shrink only or skimp only, so you always know what the number is measuring.
What the bands mean
Where the numbers come from
Every figure on a published product page is traced to a source, and we link it. We mark each data point as one of two kinds.
Documented by us against a named, dated source: news reporting, consumer-group investigations, retailer listings or manufacturer statements.
Tips from shoppers. These land in our inbox as pending and are checked against a source before anything is published. Nothing goes live on a single word.
The honest small print
- We compare the oldest and newest records we hold, not every change in between. A pack may have shrunk in steps.
- Shelf prices move and vary by retailer. Where a price is not on record we say the rise assumes the price held, and we flag it.
- A smaller pack or a cheaper recipe is not always a con. Sometimes there is a reason. We give you the figures so you can decide.
Spotted one we have missed?
Send us the old size, the new size, and where you saw it. We do the maths and the digging.
Submit a shrink