Soffit Calculator

Calculate soffit area under roof overhangs.

SOFFIT AREA
— sq ft
under overhangs

Usage Tip

Vented soffit should provide about 1 sq ft of net free area per 150 sq ft of attic floor.

THE MATH
Area = Perimeter × Overhang ÷ 12
Where: overhang in inches  •  J-channel = 2 × perimeter
• A 4×8 panel covers 32 sq ft
• Vented soffit: 1 sq ft net free area per 150 sq ft attic
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