Cannabis Dehumidifier Sizing Calculator

Most water that stays in the room eventually reaches the air. A unit sized only from a daily average can still fall behind during the highest hourly moisture load.

1. Enter one day of water delivered, runoff removed, and other water that did not return to the room air.
2. If you know the actual daily room load from condensate records, use the override.
3. Enter when the water is released and add realistic capacity loss and extra capacity.
4. For cost per pound, open the optional section and enter measured power, runtime, cycle days, and dry harvest weight.

• Use several representative late-flower days, not one unusually light irrigation day.
• Compare the estimate with collected condensate and investigate large differences.
• Check rated capacity at your actual temperature and RH, not only the favorable test condition on the label.

This is a water-load estimate, not final equipment selection. It does not include humid outside air, washdown water, standing water, or redundancy.

Sources

• Collado et al. (2024): Supplemental lighting and cannabis water use
• Collado et al. (2025): Vegetative and reproductive lighting interactions
• U.S. DOE field example: Dehumidifier capacity derating and heat rejection