Greenhouse Fans Chart

This chart shows the typical # of degrees warmer the inside of the greenhouse will be versus the outside air temperature if the ventilation system is running constantly.


- Chart assumes the exhaust fan and intake(s) are installed in opposite end walls (as shown below without any other openings near the fan).

- Chart does not take into account any other type of cooling accessories like shade and/or misting or other evaporative cooling equipment.

Greenhouse Fan CFM Calculator
Length of Greenhouse (feet)
Greenhouse Exhaust Fan
Width of Greenhouse (feet)
Peak Height of Greenhouse (feet)
W x L x H x 0.85
Fan CFM Needed - This is the optimal exhaust fan CFM (Cubic Feet per Minute) rating for your greenhouse. A fan this size will exchange the air in your greenhouse at least once per minute which is recommended for venting small greenhouses.
Greenhouse Evaporative Cooler CFM Calculator
Cooler CFM needed with no shade cover on the greenhouse.
Cooler CFM needed with a 50% or higher shade cover.

Note: You need to have Javascript enabled on your browser for the calculator to work.


Greenhouse Shutter Size Calculator
Cooler/Exhaust Fan CFM
(Use fan's max CFM rating)
Choosing Shutters
This calculator provides you with the recommended intake shutter sizes for the fan CFM specified. Two shutters are recommended for greenhouses over 10 ft. wide to provide better distribution of fresh air.

NOTE: Using smaller intakes than recommended can reduce the amount of air the fan moves and cause the motor to overheat and/or wear out prematurely.
  Minimum Intake Size
Size if using One Shutter (inches)
Size if using Two Shutters (inches)
Size if using Four Shutters (inches)

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