Plumbing Pipe Size Reference
Reference guide for plumbing pipe sizes by application.
| Size | OD (in) | ID (in) | Flow (GPM) | Material | Common Use |
|---|---|---|---|---|---|
| 3/8" | 0.675 | 0.493 | 1.5 | Copper/PEX | Supply risers, fixture connections |
| 1/2" | 0.875 | 0.625 | 4 | Copper/PEX/CPVC | Individual fixture supply lines |
| 3/4" | 1.125 | 0.875 | 8 | Copper/PEX/CPVC | Main supply to bathrooms, kitchen |
| 1" | 1.375 | 1.097 | 15 | Copper/PEX | Main water supply line |
| 1-1/4" | 1.625 | 1.368 | 22 | Copper/PEX | Main supply, sprinkler systems |
| 1-1/2" | 1.9 | 1.61 | 30 | PVC/ABS | Drain: sink, tub, shower |
| 2" | 2.375 | 2.067 | 45 | PVC/ABS | Drain: shower, laundry, kitchen |
| 3" | 3.5 | 3.068 | 85 | PVC/ABS/Cast Iron | Drain: toilet, main drain |
| 4" | 4.5 | 4.026 | 150 | PVC/ABS/Cast Iron | Main sewer line, building drain |
| 6" | 6.625 | 6.065 | 350 | PVC/Cast Iron | Building sewer, commercial |
DFU = Drainage Fixture Unit. Check local plumbing codes for specific requirements. Minimum slope for drain pipes: 1/4" per foot.