Use the same currency for both foods before comparing cost per gram of protein. A bare “$” is not enough to tell you whether two prices belong to the same market. Keep tax, discounts and the amount purchased explicit too.
Compare one consistent example
Imagine two local products priced in the same fictional currency units. A costs 4.80 and provides 60 g package protein. B costs 5.40 and provides 90 g. A costs 0.08 per gram; B costs 0.06. B is more expensive at the checkout but cheaper per documented gram of protein.
Do not compare across currencies blindly
If A is priced in one currency and B in another, those ratios are not directly comparable. A current exchange rate is needed, and a converted retail price may still describe different tax or delivery assumptions. GetMacros does not supply current exchange rates or guaranteed local prices.
Keep the purchase decision wider than the ratio
The lower ratio does not account for taste, usable shelf life or whether you will use the whole pack. It also does not rank all nutrients. Package protein must come from matching edible weight and label values; container or discarded-food mass should not inflate it.
The example prices are invented. FDA’s serving explanation supports the protein basis; the cost divisions are original arithmetic. The protein-cost calculator can compare inputs you provide, but it cannot validate a store price, currency or promotion for you. Write those assumptions beside your result.
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.