The nutrition panel and serving sizes

The panel is where a drink's commercial positioning meets arithmetic it cannot argue with.

Beverages have their own serving rules

Serving sizes are set by regulation rather than chosen by the maker, based on the amount customarily consumed, and beverages have their own reference amounts.

Which means you do not get to declare a small serving to make the sugar figure look better. The reference amount decides it.

Servings per container

The rule that surprises people. A container that holds an amount a person would reasonably drink in one sitting is labeled as a single serving, even if the reference amount is smaller.

So a bottle a customer drinks in one go declares the whole bottle's sugar in one column, rather than splitting it into two servings.

That is the intent of the rule and it is the single biggest labeling consequence of choosing a bottle size, which is why the size decision and the nutrition panel belong in the same conversation.

Added sugars

Declared separately from total sugars, and it is the number customers and retailers actually read.

A fermented product is an interesting case: sugar added and then consumed by the culture is not all present in the finished drink.

What is declared should reflect the product as sold, which is a measurement question rather than a recipe calculation, and it argues for analyzing the finished product rather than computing from the formula.

Getting the numbers

Laboratory analysis of the finished product, or a database calculation from the recipe where that is appropriate for your product.

For a fermented or otherwise transformed product, analysis is the defensible route, because the composition has changed since the ingredients went in.

Re-run it on reformulation, and keep the analysis with the label version it supports.

References