Guides
Supermarkets are very good at making individual prices look wonderful while the total quietly climbs. These guides explain the maths behind the shelf edge — the same maths BasketBadger runs on your basket — in plain language.
How to read the examples: the baskets and prices in these guides are worked examples chosen to make the arithmetic visible. They are not live prices, a promise that a named retailer offers a particular deal today, or a claim about what your household will pay. Retailer terms change, and the final price is always the one at that retailer's till or checkout.
The guides are published by BasketBadger to explain the same principles used by the app. Retailers do not approve them, sponsor their position or pay to be mentioned. Read about BasketBadger and our affiliate disclosure for who publishes this site and how it is funded.
How we compare your whole basket, not just a few prices
Why the "cheapest store" headlines mislead, what loss leaders are doing to your total, and the five things a fair comparison has to count before it names a winner.
Meal deals, multibuys and BOGOFs: how the maths really works
The worked numbers behind the three big promotion types — including the situations where taking the deal costs more than skipping it.
Click & collect vs delivery: counting the full cost
Slot fees, minimum baskets, picking charges, substitutions and your own time: how to compare getting the shopping home like-for-like.
Loyalty prices explained: Clubcard, Nectar and the two-price shelf
Why shelves now carry two prices, what the gap between them is really telling you, and how to judge whether a loyalty price is a saving or a steering wheel.