Search this and you'll find plenty of comparisons claiming one supermarket beats the other. Most of them are looking at a snapshot — one basket, one week. The honest answer is less satisfying: across a full weekly shop, Woolworths and Coles usually land close to each other overall. Neither one is reliably cheaper across the board.
Both stores run enormous numbers of individual specials every week, and they don't run the same ones. Milk might be cheaper at Coles this Monday and cheaper at Woolworths the Monday after. Multiply that across everything a household buys in a week, and the “cheapest basket” is a moving target that changes store by store, item by item, week by week.
That's genuinely hard to track by hand. It means checking both stores' current prices against your actual shopping list, every single week, before you've even started shopping. Nobody has time to do that item by item.
Not “we think Woolworths is cheaper” — a real, item-by-item price check across both stores, every week, matched against what your household actually buys. Some weeks your basket leans Woolworths, some weeks Coles, most weeks a genuine split between both. You see exactly which store each item comes from and why, every time.
If you're looking for bigger savings than switching between these two: home brands and Aldi typically move the needle more than choosing between Woolworths and Coles alone. SuperCarto already flags home-brand swaps worth making — that's a separate, honest lever from “which of these two stores,” and worth knowing rather than glossing over.