Water Pipe Sizing Calculator
Size water supply pipes based on fixture units and velocity limits.
Water Supply Pipe Sizing (GPM)
Maximum flow at 8 fps velocity
| Nominal Size | Copper L | PEX |
|---|---|---|
| 1/2" | 7.6 GPM | 5.8 GPM |
| 3/4" | 15.7 GPM | 11.5 GPM |
| 1" | 26.8 GPM | 19.0 GPM |
| 1-1/4" | 40.9 GPM | - |
| 1-1/2" | 57.9 GPM | - |
| 2" | 100.7 GPM | - |
Velocity Guidelines
- 5 fps: Quiet residential, noise-sensitive areas
- 8 fps: Standard residential and commercial
- 10 fps: Commercial/industrial (may cause noise)
- Hot water: Generally limited to 5 fps to prevent erosion