Our law says that the portion sizes must be the amount that people typically consume at once. Which conceptually makes a lot of sense. Nutrition facts per 100g

Our law says that the portion sizes must be the amount that people typically consume at once. Which conceptually makes a lot of sense. Nutrition facts per 100g is conceptually nice, but if the amount people typically eat at once is not 100g, then that means more math. Furthermore, in the US most recipes are not done by weight, so to be useful for recpie calulation, we would need to use say per 8 fl oz for liquids, a per The problem with the US system is more that the FDA implements it based on survey results for categories of food, and only occasionally update the value. This means that food that falls in one category, but that consumers treat like it falls in a different one can get laughable portion sizes, and the same thing happens when the values become out of date. Manufacturers don't really get a lot of discretion on choosing the listed serving size for most foods, with only a few places where the rules let a manufacturer choose (like for discrete units that take more than half and less than two thirds of the RACC, where the manufacturer can choose between a service size of one or two units). There are cases where manufacturers would prefer to list a different size (usually larger) because they know it is more accurate representation of what people consume, but they can't. This is hardly the only issue. Some of the rounding rules can be rather absurd, meaning that is is not always possible to get accurate information for larger sizes by simply multiplying the values on the nutrition facts label.