DWV Pipe Sizing Calculator (Drain, Waste, Vent)

How many fixtures can a 2-inch drain handle?

Under the IPC, a 2-inch horizontal branch at 1/4 inch-per-foot slope carries up to about 6 DFU, and a 2-inch stack handles more. That covers a shower, lavatory, and kitchen sink, but never a water closet — toilets require a minimum 3-inch drain regardless of fixture-unit count.

Related questions

• What size drain pipe do I need for a bathroom?
• Does every plumbing fixture need its own vent?