How to calculate protein from food labels and portions
Use the protein value and the amount of food that value describes. Then scale it to the portion you ate. The same arithmetic works for a packaged snack, a saved food or an ingredient in a meal.
Start with the basis on the label
Find the protein row and check the column heading: per 100 g, per serving or per package. Do not multiply a per-serving value by the number of grams as though it were per 100 g.
For a label showing 10 g protein per 100 g, a 150 g portion gives 150 × 10 ÷ 100 = 15 g protein. These are illustrative label values.
Convert a serving or package value
If a 40 g serving provides 12 g protein, a 60 g portion gives 60 × 12 ÷ 40 = 18 g. If you eat the whole package and the protein value is already for that package, use that value once.
When the label uses millilitres, keep both quantities in millilitres. Do not equate ml with g without a known density. A scoop or slice needs its own weight before conversion to grams.
Keep raw and cooked entries separate
Use the preparation state that matches the weight you measured. Cooking can change water content, so a cooked weight cannot simply be paired with a raw per-100-g value.
For a batch recipe, add the protein of all ingredients using their matching weights. For an evenly mixed finished batch, your portion’s share is portion weight ÷ total cooked batch weight. Unevenly distributed ingredients need separate attention. Drained liquid or discarded ingredients can also change the batch total, so this remains an estimate.
Check a scan before saving
In Protio, check the matched product, printed basis and portion. A barcode lookup can differ from your current package; a label scan can misread a number. Correct the values before logging.
Use the calculator below to check the arithmetic, then save a food or meal template if you often repeat it.
Check protein in your portion
Use grams in every field. These sample values illustrate the calculation, not a recommended portion.