Packages are designed to make comparison hard. Enter price and quantity for two products and see the price per unit — the only fair comparison.
Shrinkflation makes unit prices more relevant than ever: the package price stays the same while contents quietly shrink. Bigger packs are usually, but not always, cheaper per unit — promotions on small sizes often flip it.
The comparison needs the same unit on both sides, which is the step packaging is designed to obscure: 750 g against 1 kg, six rolls against four long ones, concentrate against ready-to-use. Convert first, then divide. A price per 100 g and a price per kilogram differ by a factor of ten and look almost identical on a shelf label.
Unit price answers "cheaper per gram", not "cheaper for me". The larger pack wins on unit price and loses on everything else if half of it spoils, and a bulk buy that ties up cash you need this week is expensive in a way no shelf label can show.
Shelf labels usually carry a unit price already, and it is worth reading rather than trusting: retailers are not always consistent about which unit they use within a category, so the same aisle can show price per 100 g, per kilogram and per item, none of which compare directly.
Frequently asked questions
How do I compare prices per kilogram?
Divide each price by its quantity in the same unit: €3.60 for 750 g is €4.80/kg, more than €4.50/kg for a 2 kg pack at €9. The lower unit price wins.
What is shrinkflation?
Reducing package contents while keeping the price — the price per pack looks stable while the price per unit quietly rises. Unit-price comparison is the antidote.
Are bigger packs always cheaper per unit?
Usually but not reliably: promotions on small sizes often make them temporarily cheaper per unit. Check the shelf's unit price rather than assuming.