Grow Room Humidifier Sizing Calculator
Find the L/hr or pints per day output you need from room size, temperature, and humidity targets.
Measure at canopy level.
Propagation 65 to 80, veg 55 to 70, flower 40 to 55.
Sealed rooms 1 to 2, ventilated rooms 3 to 6, high airflow 6 to 10+.
Headroom for door openings, leaks, and unit wear. 20 to 30% is common.
Selecting a stage sets the target RH above.
Hotter fixtures dry the air faster.
Recommended humidifier output
0.00
L/hr
0 pints/day
- Room volume
- 0 ft³
- Moisture deficit
- 0.00 g/m³
- Minimum required
- 0.00 L/hr
- Minimum in pints/day
- 0 PPD
Pick a unit rated at or above the recommended output. 1 L/hr is about 50.7 pints per day.
How this is calculated
Absolute humidity (g/m³) is computed at your air temperature for the current and target RH using the Magnus saturation vapor pressure equation. The difference is the moisture deficit. Required output (L/hr) = deficit × room volume (m³) × air changes per hour ÷ 1,000, multiplied by the light type factor. The recommended figure adds the sizing buffer. Simple mode uses 3 ACH and a 25% buffer.