When a multibuy costs you more
A multibuy is a discount on the item and an increase in the bill. Those are not the same thing.
Two for one. Three for the price of two. Second item half price. Every one of these lowers the cost per item, and every one of them raises what you spend in that visit. Both statements are true at once, and which one matters depends entirely on whether you were going to buy two anyway.
The question that settles it
Would you have bought the second one at full price?
If yes, the offer is a straightforward saving and you should take it. If no, then you have not saved anything — you have spent money on a second item you did not want, at a discount. The discount is real. The purchase was manufactured by the offer.
This sounds obvious written down. It is remarkably hard to apply while holding the second item.
Where multibuys are genuinely good
They work best when three things are true: you use the item constantly, it does not spoil, and you have somewhere to put it.
- Cleaning products, toilet roll, washing detergent
- Tinned and dried food you actually cook with
- Pet food for a pet you already have
- Anything with a long date that you would restock within a month or two regardless
For these, a multibuy is genuinely just a lower price on something already on your list.
Where they quietly cost you
- Fresh food. A saving on the second punnet is not a saving if it goes in the bin. Household food waste is where multibuy savings most often evaporate.
- Things you were not buying. The offer created the purchase. The comparison is not "cheaper per item", it is "money spent versus money not spent".
- Items where the single price rose first. The single-unit price can move up as the offer goes live, so the bundle is measured against a number that only exists to make it look good.
- Own-brand alternatives. A branded 2-for-1 frequently still costs more per unit than the own-brand equivalent at its ordinary price. The offer invites you to compare the brand against itself.
Reading the shelf properly
| Offer | What to check |
|---|---|
| 2 for £X | The unit price of the deal against the single unit price of every alternative |
| Second half price | Whether the first item is priced competitively at all — half of an inflated price is not a bargain |
| 3 for 2 | Whether you will genuinely use three before they expire |
| Meal deals and bundles | The total against buying only the parts you actually want |
| Loyalty-only pricing | Whether the non-member price rose to create the gap |
The shorter version
A multibuy is worth taking on things you already buy, and worth ignoring on things it introduced you to. The offer is designed to blur that line, so decide before you look at it: what was on the list, and what was not.