How many fixtures can you put on a 3 inch vent pipe?

The number of fixtures you can connect to a 3-inch vent pipe depends on several factors, including local Plumbing codes and the type of fixtures being used. Generally, a 3-inch vent pipe can accommodate up to 15 fixture units, but this can vary based on specific regulations and the types of fixtures involved. It's essential to consult local plumbing codes and possibly a professional plumber to ensure compliance and proper functionality.