Three for the Price of Two of Nothing: Our Four-Week Multibuy Audit Found Some Offers Aren't Offers at All

Multibuys are the confetti of the supermarket aisle. They're everywhere, they're cheerful, and half the time you're not entirely sure what they're actually worth. So we decided to find out properly. For four weeks, one of our writers logged every multibuy promotion she encountered — 143 offers across six supermarkets and a handful of high street retailers — and wrote down the promoted price alongside the ordinary unit price for the same item.

The results were, in a word, mixed. In two words: occasionally embarrassing.

The Good News First: Some Multibuys Are Genuinely Brilliant

Let's not paint the whole shelf yellow. Roughly a third of the offers we tracked delivered real, honest savings — the kind you'd happily tell your mate about.

The standouts were almost always on items we'd buy anyway. A 3 for £10 deal on packs of chicken breasts worked out at 22% less per kilo than the single-pack price. Cereal multipacks, tinned tomatoes, loo roll — the boring, non-perishable staples were where multibuys consistently earned their keep.

The pattern was clear: the less exciting the product, the more honest the deal. Nobody builds a marketing campaign around tinned kidney beans, so the discounts on them tend to be real.

The BOGOF Illusion

Buy one get one free sounds like the purest form of a discount — you literally get something for nothing. Except, as we kept finding, the 'free' one is often priced in.

Take the yoghurts. A four-pack on BOGOF worked out at 62p per pack. Sounds great, until you notice the eight-pack sitting two shelves down at £2.10 — that's 52p per pack, every week, no promotion required. The BOGOF was only a deal if you'd never noticed the bigger pack existed.

We found the same trick with laundry tablets, razors, and — most painfully — a famous brand of crisps where the BOGOF price per bag was actually 4p more than the sharing bag. We stood in the aisle double-checking that one. We hadn't misread it.

'3 for £10': The Maths Nobody Does at the Shelf

The 3-for-£10 format deserves its own paragraph, because it's the sneakiest of the lot. These offers rarely advertise what you're saving — they just present a tidy round number and let your brain assume it's a bargain.

Of the nineteen 3-for-£10 deals we logged, seven were on items where buying three individually cost £10.40 or less. One wine offer — three bottles for a tenner — saved you precisely 15p on bottles that were £3.35 each. Fifteen pence. For the privilege of buying three bottles instead of one.

The fix here is simple and takes two seconds: divide the multibuy price by the quantity, then glance at the unit price on the shelf edge label. If the £/kg or £/litre figures don't back up the hype, the hype is wrong.

The Fresh Food Problem

Here's where multibuys get genuinely costly. Roughly 40% of the offers we tracked were on fresh produce — salad bags, berries, bread, chilled ready meals. These are exactly the items most likely to die in your fridge before you get to them.

A BOGOF on two bags of salad is only a saving if you eat both bags. Our writer's food waste bin told the real story of week three: two mouldy punnets of 'free' strawberries and half a 3-for-£2 bread deal gone stale. The promotion saved money on paper and cost money in the bin.

If you can't freeze it, decant it, or genuinely eat double the quantity, a fresh-food multibuy isn't a deal — it's a donation to your caddy.

Our Retailer Scorecard

After four weeks and 143 offers, here's how the multibuy culture shaped up at each retailer we visited:

• Most honest multibuys: Aldi and Lidl, largely by accident — they run fewer promotions overall, so the ones they do run tend to be straightforward price cuts rather than clever arithmetic.
• Best for stock-up deals: Tesco and Sainsbury's, whose offers on long-life staples were consistently genuine — though you'll need a Clubcard or Nectar card to get the advertised price at both.
• Most likely to mislead: The big four's branded-goods promotions, where the 'offer' price frequently matched or beat the permanent larger-pack price. Check before you cheer.
• High street 3-for-2s: Toiletries and cosmetics were the worst offenders. Several '3 for 2' gift-set deals were beaten by simply buying the items from the supermarket's own-brand range instead.

The Takeaway

Multibuys aren't scams — they're tools, and like any tool, they're only useful for the right job. The rules we've landed on after this experiment:

1. Only take a multibuy on something already on your list. A deal on something you weren't buying is a 100% markup from £0.
2. Check the unit price, always. Ten seconds at the shelf edge has saved us pounds this month.
3. Never multibuy fresh food you can't finish. The bin doesn't issue refunds.
4. Bigger packs often beat promotions. The everyday large size is the multibuy's quiet, better-value rival.

Do that, and the offers that survive your scrutiny will be the genuinely good ones. Everything else is just confetti.