Drain Pipe Sizing Calculator
Size DWV piping based on drainage fixture unit loading.
Horizontal Drain Capacity (DFU)
| Pipe Size | 1/8" Slope | 1/4" Slope | 1/2" Slope |
|---|---|---|---|
| 1-1/2" | 1 | 1 | 1 |
| 2" | - | 8 | 9 |
| 3" | 20 | 27 | 36 |
| 4" | 180 | 216 | 250 |
| 5" | 390 | 480 | 575 |
| 6" | 700 | 840 | 1000 |
Vertical Stack Capacity (DFU)
| Pipe Size | Total Stack | Per Branch |
|---|---|---|
| 1-1/2" | 2 | 1 |
| 2" | 6 | 4 |
| 3" | 48 | 24 |
| 4" | 256 | 90 |
| 5" | 600 | 200 |
| 6" | 1380 | 400 |