If delivery is necessary for one purchase, its cost belongs in that purchase comparison. Comparing only the food’s sticker price can produce the wrong ranking. If the fee is shared with other shopping, state how you allocate it rather than pretending the allocation is objective.
A ranking that reverses
Imagine a local product costing 8 units for 80 g package protein. Its ratio is 0.10 per gram. An online product costs 7 for 100 g, or 0.07 before delivery. Add an unavoidable 5-unit delivery fee and the online purchase becomes 12 ÷ 100 = 0.12 per gram. The local option is now cheaper on that defined basis.
Find the fee boundary
For the online ratio to equal 0.10, its total cost would be 10 units. Since the food costs 7, a fee of 3 gives a tie. Fees below 3 favor the online example; fees above 3 favor the local one, assuming all protein is used.
Keep the scope practical
Tax, minimum-order requirements and subscriptions can add other costs. Do not count an entire delivery fee against one item without explaining that choice, and do not assume a subscription is free because you already pay for it.
These are invented shopping conditions, not current offers or a claim about any retailer. The protein amount must still come from compatible label portions. This original calculation extends the serving-based method into a transparent purchase decision. It is a comparison of specified costs, not an overall health score or a guarantee of value.
Sources and example boundaries
- FDA: serving information
Serving sizes and household/metric units on U.S. labels.
All food figures and prices in the worked example are invented to explain the method. They are not restaurant nutrition, tested recipes, shopping prices or personal dietary advice. Use the current label for the product you actually have.