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Greenhouse Fan CFM Calculator

Achieving the perfect balance of air circulation is crucial for the well-being of their plants. The Greenhouse Fan CFM (Cubic Feet per Minute) Calculator is a vital tool tailored for smaller-scale greenhouse setups. It simplifies the process of determining the ideal fan size needed to maintain optimal ventilation, ensuring a thriving environment for your greenhouse garden.

Our calculator provides a user-friendly interface where you simply enter the dimensions of your greenhouse – height, width, and length – along with your chosen multiplier. Upon clicking the ‘Calculate’ button, the calculator processes these inputs and delivers the recommended CFM rating for your greenhouse fan.

Quonset Hut
Quonset Hut
Gabled A-frame
Gabled A-frame
Lean-to
Lean-to
Geodesic Dome
Geodesic Dome






CFM (Cubic Feet per Minute) represents the volume of air moved by a fan per minute. In a standard setup, the CFM value equals the greenhouse’s total volume for a one-minute air exchange. For instance, a greenhouse with a volume of 1000 cubic feet requires a fan with a 1000 CFM rating for a standard air exchange. The air exchange rate is adjustable here as a percentage. Using 100% sets the exchange rate to this standard level. If you wish to increase the rate of air exchange—resulting in faster air turnover—simply increase the percentage. For example, setting it to 150% implies an exchange rate of 1.5 times the standard volume per minute, necessitating a fan with a 1500 CFM rating.

Benefits of Using the Correct CFM Rating

  1. Enhanced temperature and humidity control: In areas with fluctuating climates or in densely planted greenhouses, proper ventilation is crucial. A higher CFM rating ensures better control over these environmental factors.
  2. Safety margin: The calculator helps in determining a CFM rating that offers a safety margin. This ensures that your ventilation system remains effective even in less-than-ideal conditions, like when vents are partially blocked.
  3. Customization: The multiplier adjustment feature allows for customization based on the specific conditions and needs of your greenhouse, ensuring that the ventilation system is precisely tailored to maintain desired conditions.