Turn a per-100-g panel into a 65 g portion
Convert a European nutrition panel into a weighed portion and reverse-check the arithmetic without treating 100 g as a suggested serving.
A per-100-g panel supplies a common comparison basis. Your portion can be smaller or larger. To estimate the nutrient quantity in a weighed portion, multiply the printed per-100-g amount by the portion weight and divide by 100.
Article 32 of the EU food information regulation uses a 100 g or 100 ml basis for the nutrition declaration. The examples here concern grams of food, so no volume-to-weight conversion is involved.
Work from one clearly identified column
Suppose a fictional package declares 12 g protein, 8 g sugars, and 1.2 g salt per 100 g. You weigh a 65 g portion of the food in the same state described by that panel. The multiplier is 65 ÷ 100 = 0.65.
- Protein: 12 × 0.65 = 7.8 g.
- Sugars: 8 × 0.65 = 5.2 g.
- Salt: 1.2 × 0.65 = 0.78 g.
Keep the three results under a heading such as “calculated for my 65 g portion.” Do not overwrite the printed column or relabel the result as the manufacturer's serving. The 65 g choice belongs to your worksheet.
Reverse-check a result
Take the protein estimate back to the original basis: 7.8 ÷ 65 × 100 = 12 g per 100 g. If that check fails, look for a missing division by 100 or a copied value from a different column.
A particularly easy error is entering 65 as the multiplier rather than 0.65. The resulting 780 g protein would exceed the 65 g food portion and expose the arithmetic mistake. Plausibility checks do not prove accuracy, but they can catch a misplaced decimal quickly.
Keep preparation and leftovers separate
If the label describes dry food and your scale holds cooked food, 65 g is not yet a matching denominator. You need information about the prepared yield or a corresponding prepared-food panel. Water added during cooking changes weight without necessarily adding the nutrient being compared.
Likewise, weigh the edible portion relevant to your calculation rather than the bowl or wrapper. Use the package's stated drained or prepared basis where applicable. This worksheet estimates quantities from declared averages; it does not establish personal requirements or assign an overall health score to the food.