Floor Drain Sizing Calculator
Size floor drains per UPC/IPC requirements
Drainage Area
Flow Parameters
Equipment discharge, hose bibs, etc.
Drain Requirements
Minimum Drain Size
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Per-Drain Capacity
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Total Drainage Area
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Design Flow Rate
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Drain Fixture Units
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Max Distance to Drain
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Code Note: Floor drains must have trap primer or trap seal maintenance device per UPC/IPC.
Floor Drain Capacities
| Drain Size | DFU Rating | Max GPM | Max Area (sf) |
|---|---|---|---|
| 2" | 2 | 12 | 200 |
| 3" | 4 | 27 | 400 |
| 4" | 8 | 50 | 800 |
| 6" | 16 | 100 | 1,600 |
| 8" | 32 | 175 | 3,000 |
Floor Drain Requirements by Application
Restrooms
3" minimum
1 per 400 sf
Trap primer required
Commercial Kitchen
4" typical
1 per 200 sf
Grease interceptor
Industrial
4"-6" typical
Based on flow
May need acid resistant
Parking
4"-8" typical
1 per 500-1000 sf
Oil/sand interceptor
Installation Requirements
Floor Slope
- 1/8" per ft minimum
- 1/4" per ft typical
- Max 25 ft to drain
- 2% max for ADA
Trap Protection
- Trap primer connection
- Trap seal primer device
- Deep seal trap (4"+)
- Weekly maintenance option
Strainer/Grate
- ADA compliant pattern
- 1/4" max openings
- Heel-proof for walking
- Heavy duty for traffic