Attic Ventilation Calculator
Calculate the proper amount of attic ventilation needed. Get intake and exhaust vent requirements based on attic size.
Attic Details
1,500 sq ft
500 sq ft5,000 sq ft
sq ft
6:12
2:1212:12
Climate Zone:
Ventilation Type:
Net Free Vent Area (NFVA) Needed
720 sq in
(5.00 sq ft total ventilation)
⬇️Intake Area
360 sq in
⬆️Exhaust Area
360 sq in
Recommended Vents:
Intake Options
6 soffit vents
Standard 8" x 16" vents
Exhaust Option 1
20 ft ridge vent
Exhaust Option 2
8 box/roof vents
Power Ventilator Alternative:
1050 CFM minimum
Ventilation Standards
1:150 Rule (No Vapor Barrier)
1 sq ft ventilation per 150 sq ft of attic floor
1:300 Rule (With Vapor Barrier)
1 sq ft ventilation per 300 sq ft of attic floor