> Most food labeling in the US is done this way. Gross measures (total volume, weight, etc) are in imperial while the nutrition facts are in metric. So milk will say, serving size 12 Oz, protein XX g.

Both net contents and serving size include metric measures.

"Food labels printed must show the net contents in both metric (grams, kilograms, milliliters, liters) and U.S. Customary System (ounces, pounds, fluid ounces) terms." [0]

"The serving size is expressed as a common household measure followed by the equivalent metric quantity in parenthesis." [1]

[0] https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocument...

[1] https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocument...