Ridge Vent Calculator
Calculate the correct ridge vent length for proper attic ventilation with our comprehensive calculator. Determine optimal ventilation based on attic area, roof pitch, and building code requirements.
Step 1: Attic Specifications
Understanding Attic Ventilation
Proper attic ventilation prevents moisture buildup, reduces energy costs, and extends roof life. The 1/300 rule requires 1 sq ft of ventilation per 300 sq ft of attic floor area.
Step 2: Ventilation Parameters
About Net Free Area (NFA)
Net Free Area is the unobstructed area through which air can pass. Higher NFA ratings mean better airflow. Ridge vents typically provide 9-18 sq inches of NFA per linear foot.
Ridge Vent Calculation Results
Required Ridge Vent Length
Ventilation Type Comparison
| Ventilation Type | NFA per ft | Required Length | Total NFA |
|---|
Ventilation Calculation Breakdown
Ventilation Formula
Required Vent Area = Attic Area ÷ Ventilation Ratio
Ridge Vent Length = (Required Vent Area × 144) ÷ Ridge Vent NFA per ft
To calculate: Divide attic area by ventilation ratio (e.g., 300), convert to square inches (×144), then divide by ridge vent NFA rating per linear foot.
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