On average, the composition of Holstein milk is 87.7 percent water, 3.7 percent milk fat and 8.6 percent skim solids.

FORBES: Why Milk Isn't As "Natural" As You Think

Milk that is in its final package form for beverage use shall have been pasteurized or ultrapasteurized, and shall contain not less than 8.25% solids and not less than 3.25% milk fat .

FORBES: Why Milk Isn't As "Natural" As You Think