Best Attic Fans: Roof-Mount, Gable, Solar and Whole-House Fans
What each type does, how to size it in CFM, the intake venting it needs, and why an attic fan and a whole-house fan are different machines.
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An attic fan exhausts hot air from the attic; a whole-house fan pulls cool evening air through open windows and pushes the house's warm air out through the attic. Both only work with enough intake to replace the air they move, and neither should run next to a ridge vent that will short-circuit it.
For solar-only models, see our solar attic fan guide. This guide compares all four types by specification; it is not a hands-on product test.
Compared by type
Pros and cons describe each type from its specifications; this is not a hands-on product test. As an Amazon Associate we earn from qualifying purchases.
Roof-mount powered attic ventilator
Best for: Large or dark-roof attics without a ridge vent. Check: CFM rating, adjustable thermostat (and humidistat), and a fire-safety cut-off.
Pros
Highest, steadiest attic airflow
Thermostat runs it only when needed
Works at night and in cloud
Cons
Needs a wired circuit and costs money to run
Another roof penetration to flash
Can pull conditioned air from a leaky ceiling
Gable-mount fan
Best for: Attics with gable louvres and no ridge vent. Check: Fits behind your louvre and the rated CFM.
Pros
No new hole in the roof
Easy to service from inside the attic
Mains and solar versions
Cons
Can pull air in through the opposite gable instead of the soffits
Less effective on hip roofs
Mains models need a circuit
Solar attic fan
Best for: Sunny climates where you want no wiring or running cost. Check: Panel wattage, rated CFM and a thermostat.
Pros
No running cost
No electrician needed
Most output on the hottest days
Cons
Stops when the sun does
Lower CFM than most mains fans
Panel angle limited on some roofs
Whole-house fan
Best for: Dry climates with cool evenings, to cut air-conditioning hours. Check: CFM for your floor area, an insulated damper door, and the attic vent area it needs.
Pros
Cools the whole house, not just the attic
Uses far less power than air conditioning
Insulated doors seal the opening in winter
Cons
Only useful when outside air is cooler than inside
Needs open windows while it runs
Needs a lot of attic exhaust venting
Sizing an attic fan
Worked example: A 1,500 sq ft attic
1,500 × 0.7 CFM per sq ft = 1,050 CFM
Dark roof or very hot climate: + 15% = 1,208 CFM
Intake at about 1 sq ft per 300 CFM: 3.5 sq ft (504 sq in) of free soffit area
Look for 1,050–1,208 CFM of fan, plus 3.5 sq ft of clear soffit intake. Check your vents with the [attic ventilation calculator](/attic-ventilation-calculator/).
Sizing a whole-house fan
A common guide is 2 to 3 CFM per square foot of living space, with the upper end for hot climates. Manufacturers then ask for attic exhaust venting — often around 1 sq ft of net free area per 750 CFM; use the figure in the fan's own manual.
Worked example: A 1,800 sq ft house
1,800 × 2 to 3 CFM = 3,600–5,400 CFM
Attic exhaust at 1 sq ft per 750 CFM: 3,600 ÷ 750 = 4.8 sq ft or more
A 3,600–5,400 CFM fan with at least 4.8 sq ft of attic venting. Run your house through the [whole-house fan calculator](/insulation-calculator/whole-house-fan-calculator/).
When a fan is the wrong fix
You have a ridge vent: an attic fan pulls air in through it instead of the soffits.
The soffits are blocked: clear them and add rafter baffles first — often that fixes the heat on its own.
The ceiling leaks air: air-seal it, or the fan pulls conditioned air (and, with natural-draught gas appliances, possibly flue gases) into the attic.
The problem is winter frost or ice dams: that is air sealing, insulation and passive venting, not a fan.
Safety notes
Mains-powered fans need a fire-safety cut-off and wiring to code; hire a licensed electrician if you are not qualified.
Whole-house fans must only run with windows open, and homes with natural-draught gas appliances should be checked by a professional first.
Cutting a roof or ceiling opening means working at height and around framing — use fall protection and cut only between rafters or joists.
Frequently asked questions
What is the best attic fan?
For a large attic without a ridge vent, a roof-mount powered ventilator with a thermostat and fire cut-off; with gable vents, a gable-mount fan; for no wiring, a solar fan. All need enough soffit intake.
What is the difference between an attic fan and a whole-house fan?
An attic fan exhausts hot attic air only. A whole-house fan sits in the ceiling and pulls outside air through open windows, flushing heat from the whole house into the attic and out of its vents.
What size attic fan do I need?
About 0.7 CFM per square foot of attic floor, plus 15% for a dark roof or hot climate. A 1,500 sq ft attic needs roughly 1,050 to 1,200 CFM.
Can I use an attic fan with a ridge vent?
It is not recommended. The fan draws air through the ridge vent instead of the soffits, so the lower attic is not ventilated and rain can be pulled in.
Are whole-house fans worth it?
In climates with cool, dry evenings they can replace many hours of air conditioning at a fraction of the power. In hot, humid climates where nights stay warm, they help much less.