The lawsuits, filed in Pennsylvania, California and other states, claim consumers have been cheated out of the alcohol content stated on labels.
Budweiser and Michelob boast of being 5% alcohol, while some "light" versions are said to be just over 4%.
The lawsuits are based on information from former employees at the company's 13 US breweries, some in top-level plant positions, according to lead lawyer Josh Boxer of San Rafael, California.
"Our information comes from former employees at Anheuser-Busch who have informed us that as a matter of corporate practice, all of their products mentioned [in the lawsuit] are watered down," Mr Boxer said. "It's a simple cost-saving measure, and it's very significant."
Anheuser-Busch InBev said the claims were groundless .