Domestic Water Pipe Sizer

Size cold & hot water supply piping per IPC / UPC

Plumbing Code

International Plumbing Code 2021

Input Method

Flow Rate (GPM)

Most Demanding Fixture (for pressure check)

Pressure Budget

Available Pressure (PSI)

Elevation to Fixture (ft)

System Losses (PSI)

Pipe Run Length (ft)

System losses include meter, backflow preventer, valves — default 10 PSI covers most commercial systems

Max Velocity (FPS)

IPC max 8 FPS

Mode

IPC 2021 — Fixture Unit Values (WSFU)

Table E103.3(2)

FixtureWSFUMin PSI

Water Closet (Flushometer Valve)1035

Water Closet (Flush Tank)2.58

Urinal (Flushometer Valve)525

Lavatory (Public)1.58

Lavatory (Private)18

Shower28

Bathtub28

Kitchen Sink1.58

Service Sink38

Washing Machine28

Dishwasher1.58

Drinking Fountain0.58

Hose Bibb2.58

Source: IPC 2021 Appendix E / Table 604.3

Velocity Guidelines

IPC Code Maximum

Hard limit

8 FPS

Recommended

Noise & erosion control

4–5 FPS

Minimum recommended

Avoid stagnation

0.5 FPS

Source: IPC 2021 Section 604.3

Pressure Guidelines

Typical street pressure40–80 PSI

IPC maximum at fixture80 PSI

Elevation loss0.433 PSI/ft

Typical meter loss4–8 PSI

Typical BFP loss5–10 PSI

Min (flush tank)8 PSI

Min (flushometer valve)35 PSI

Source: IPC 2021 Tables 604.3 & 604.4