Soffit & Fascia Calculator
Soffit & Fascia Materials
Calculate soffit panels and fascia boards needed
Soffit Ventilation Requirement
Calculate how much soffit ventilation your attic needs
Formula
Soffit Area = Eave Length × Overhang Width | NFA = Attic Area / 300 (balanced) or / 150 (unbalanced) | Panels = Area / Panel Coverage × 1.10
Frequently Asked Questions
What is the difference between soffit and fascia?
Soffit is the underside of the roof overhang (horizontal, faces the ground). Fascia is the vertical board at the edge of the roof where gutters attach. Together they enclose and protect the rafter tails and provide attic ventilation.
How much soffit ventilation do I need?
Follow the 1/300 rule with balanced ventilation: 1 sq ft of Net Free Area (NFA) per 300 sq ft of attic floor area, split 50/50 between intake (soffit) and exhaust (ridge vent). Without balanced ventilation, use 1/150 ratio.
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