1:150 Ventilation Ratio Calculator

Calculate ventilation requirements using standard 1:150 ratio.

Surface area measurement (length × width for rectangles).
sq ft
Enter the vapor barrier present value for this calculation.

Results

Total NFA Required:
Sum of all calculated values.
-sq in
Intake NFA (50%):
Calculated intake nfa (50%) based on your inputs.
-sq in
Exhaust NFA (50%):
Calculated exhaust nfa (50%) based on your inputs.
-sq in
Ridge Vent @ 18 NFA/ft:
Calculated ridge vent @ 18 nfa/ft based on your inputs.
-ft
Reference: Industry Standards. FHA and IRC ventilation ratio standards.