Compare unit prices, not pack prices
A larger pack is not always cheaper per kilogram or per litre. Check the unit price and whether the pack size matches how much you will use before it spoils.
Build a repeated basket
Compare the same basket of staples across stores: rice, lentils, eggs, milk, chicken, vegetables, fruit, oil and cleaning products. A store that is cheap on one item can be expensive on another.
Store format changes the price
Hypermarkets, discounters, neighbourhood groceries and online delivery have different pricing and fees. Delivery charges and minimum orders are part of the basket cost.
Season and origin matter
Produce prices move with season and import origin. A price observed in one month is not an annual average. Keep the date and the pack size.
Waste is a cost line
Buying in bulk only saves money if the food is eaten. Plan meals and freeze portions before assuming a larger pack is better value.