Calculate Your Attic Venting

Based on your attic vent survey, there is a total net free area of square inches. This is equivalent to square feet of net free area.

Here are the requirements for our whole house fans:

Why ?
  1. Whole House Fans push air from your house into the attic. Just about all attics are vented, so the air will naturally flow outside. If you don't have enough venting area, pressure from a Whole House Fan can build up, slowing down airflow, but more importantly air could be pushed back into your living space.
  2. Each of our Whole House Fans has a listed requirement for attic venting. This is listed in units of "square foot of net free area".
  3. This straightforward calculator will allow you to determine the "net free area".
  1. Identify and measure your roof vents
  2. There are various types of vents and not all of them are in view or accessible, where you can't measure, just estimate.
  3. Enter your information, here, press submit
  4. Make sure you have sufficient attic venting for your selected WHF
Engineer's Tip

Keep your attic cooler during the day and get even better natural cooling results. By using a combination of ridge venting at the peak and under-eaves vents on the bottom, you can help create a convection current that lets hot air (lighter and more buoyant) out the top and draws cooler air in from below.

Need More Venting ?
Consider adding a
Solar Attic Fan

Besides cooling your attic during the day, a single solar attic fan can provide up to 1.0 square feet of passive venting area


Attic Vent Survey:

Attic Area

Sq. Feet  *Optional

Ridge Vent

Length (Feet)

Louvers or
Soffit Vents

Qty. L (Inches) W (Inches)

Soffit Vents

Qty. L (Inches) W (Inches)

Soffit Vents

Qty. Diameter (Inches)

Turbine Vents

Qty. Diameter (Inches)

Round Vents

Qty. Diameter (Inches)