Condensate Drain Calculator

Size condensate drain lines and calculate moisture removal rates for AC and dehumidification systems.

System Capacity

Operating Conditions

Drain Configuration

Drain Sizing Table

CapacityDrain SizeGPH Max
Up to 20 tons3/4"5
21-40 tons1"10
41-90 tons1-1/4"20
91-125 tons1-1/2"30
126-250 tons2"60

Installation Guidelines

Slope: 1/8" per foot minimum for gravity drain

P-Trap: Required for negative pressure units

Vent: Required for long runs or multiple connections

Cleanout: Install every 50 ft on horizontal runs