Put price and nutrition on the same 100 g basis
Create separate price and nutrient columns so a cheaper package is not confused with a cheaper equal quantity of food.
The lower shelf price is not necessarily the lower price for an equal amount of food. A useful shopping worksheet can place price per 100 g next to a nutrient amount per 100 g, while keeping the two measures separate.
The common weight basis follows the comparison structure in the EU nutrition declaration rules. Price arithmetic below is an original hypothetical example; these are not observed retail offers.
Calculate two independent columns
Imagine pack A weighs 250 g, costs $3.00, and declares 12 g protein per 100 g. Pack B weighs 400 g, costs $4.00, and declares 10 g protein per 100 g.
For price per 100 g, divide price by net food weight and multiply by 100. A costs $3.00 ÷ 250 × 100 = $1.20 per 100 g. B costs $4.00 ÷ 400 × 100 = $1.00 per 100 g.
| Pack | Checkout price | Price per 100 g | Protein per 100 g |
|---|---|---|---|
| A | $3.00 | $1.20 | 12 g |
| B | $4.00 | $1.00 | 10 g |
B has the higher checkout price but the lower equal-weight price. A has the higher protein concentration in this example. There is no need to compress these separate observations into a single overall winner.
Define what the price includes
Use the actual price you would pay, including any unavoidable charge allocated consistently. A membership-only offer should not be compared with an ordinary price unless you can use that membership. Keep the currency, retailer, and date with real price observations.
Also use the relevant edible quantity. If a package includes liquid you discard, comparing its full net weight with another product's drained weight creates a misleading denominator. Establish a consistent quantity basis before calculating value.
Add the intended portion if useful
For a 50 g portion, A represents $0.60 of food and 6 g protein; B represents $0.50 and 5 g. These are proportional allocations, not necessarily the cash needed at checkout.
Waste, storage, preparation, and preference can affect the practical purchase decision. The table makes its price and nutrient assumptions visible without claiming that one ratio measures all forms of value.