Ventilation & Fan Capacity (CFM) Calculator Greenhouse Fan Capacity (CFM) Calculator Length (ft): Width (ft): Average Height (ft): Efficiency Factor (Obstructions): No Obstructions (Empty Greenhouse) Standard (Plants & Shelves) Heavy (Dense foliage & Equipment) *Factors in resistance from plants and equipment. Calculate Required CFM Minimum Required Airflow: Pro Tip: Look for a fan with this rating or higher. It’s better to have a slightly stronger fan with a speed controller.
