Use this calculator to estimate your greenhouse cubic footage and get a practical starting point for fan sizing based on your structure and dimensions.
Good airflow plays an important role in managing heat, humidity, and overall growing conditions. This tool is designed to keep things simple and give you a useful starting point for smaller greenhouse setups.
Calculate Your Greenhouse Ventilation Needs
Choose your greenhouse style, enter your dimensions in feet, and adjust the air exchange rate if needed. Then click Calculate to view your recommended fan size.
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We can email your result so you have it for later while planning your greenhouse ventilation setup.
Greenhouse Fan Calculator FAQs
How does this greenhouse fan calculator work?
This calculator estimates the volume of your greenhouse and uses that space to suggest a starting CFM range for ventilation. It is meant to help you narrow down fan size, not replace a full ventilation plan. Intake airflow, greenhouse layout, glazing, climate, and sun exposure can all affect how much ventilation you actually need.
Why does greenhouse fan size matter?
If a fan is too small, heat and humidity can build up fast. If it is much oversized, airflow may be too aggressive than needed for your setup and leads to higher watering needs and other issues. Starting with the right CFM helps you make a more informed choice.
What does CFM mean?
CFM stands for cubic feet per minute. It measures how much air a fan can move in one minute.
What does “air exchange rate (%)” mean?
The air exchange rate adjusts how much airflow you want the fan to move through the greenhouse. A setting of 100% gives you a starting point based on one full air exchange per minute.
Increasing the percentage raises the airflow target, which may be useful in hotter conditions or for greenhouses that need more aggressive ventilation.
Will one exhaust fan be enough?
That depends on your greenhouse size, layout, and conditions. Smaller setups may do well with one fan, while hotter climates or larger structures may need a more complete ventilation strategy.
Need Help Choosing the Right Fan?
This calculator gives you a solid place to start, but every greenhouse behaves a little differently. If you want help thinking through your layout, climate, and airflow needs, we’re happy to help.