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Eave Overhang & Panel Engine

Soffit Calculator

Calculate total eave and rake overhang area, required 12-ft soffit panels, F-channel, J-channel, and trim fasteners.

Eave Overhang & Panel Takeoff
Width from wall to subfascia (typically 12", 16", or 24").
Recommended Panel Order
1112-ft Soffit Panels
Total Overhang Area:176.0 sq ft
Net Overhang Area160.0 sq ft
Cuts per 12-ft Panel9 cuts
F-Channel (12-ft)10 pcs (120 LF)
J-Channel (12-ft)10 pcs (120 LF)

Soffit Panel Geometry & Cross-Cut Yields

Soffit installation involves installing panels perpendicular to the wall. Calculating panel requirements requires knowing the exact cut yield per 12-foot factory panel.

Soffit Panel Yield & Channel Takeoff

Overhang Area = (Eave Length ft × Depth in / 12) + (Rake Length ft × Depth in / 12)

Variables & Units:

Cuts per Panel
⌊144 inches / Overhang Depth in inches⌋
Total Panels
⌈Total Overhang Area with 10% Waste / Panel Square Footage⌉
F/J Channel
⌈Total Perimeter Linear Feet / 12 ft pieces⌉

Worked Example: 80 LF Eave with 16-Inch Overhang

Scenario: Calculating soffit panels for an 80-foot eave run and 40-foot gable rake with a 16-inch overhang depth using 16-inch wide × 12-foot long vented panels with 10% waste.

Step 1: Calculate Net Overhang Surface Area160.0 sq ft Net Area

(80 ft × (16" ÷ 12)) + (40 ft × (16" ÷ 12)) = 106.67 + 53.33 = 160.0 sq ft

Step 2: Apply 10% Waste Factor176.0 sq ft

160.0 sq ft × 1.10 = 176.0 sq ft Total Needed

Step 3: Calculate Panel Yield & Order12 Panels (12-ft long)

16" panel has 16 sq ft per 12-ft panel -> 176.0 ÷ 16 sq ft = 11 -> 12 panels (9 cuts/panel)

Step 4: Channel Trim Schedule10 F-Channels, 10 J-Channels

120 LF total perimeter ÷ 12 ft pieces = 10 pieces F-Channel + 10 pieces J-Channel

Takeaway: Ordering 12 panels and 10 pieces each of F-channel and J-channel covers all eave and rake overhangs with clean cut margins.

Frequently Asked Questions

How do you measure a house for soffit?

Measure the total linear length of all eave overhangs and gable rakes, and measure the overhang depth from the exterior wall sheathing to the inside face of the subfascia board. Multiply length by depth to calculate total overhang square footage.

How many pieces can you cut from a 12-foot soffit panel?

Standard vinyl and aluminum soffit panels are 12 feet long (144 inches). For a standard 16-inch overhang, each panel yields 9 cuts (144 ÷ 16 = 9). For a 24-inch overhang, each panel yields exactly 6 cuts (144 ÷ 24 = 6).

What is the difference between F-channel and J-channel on soffit?

F-channel has an extended leg that mounts flat against the wall sheathing to receive the inner edge of the soffit panel. J-channel is typically used along the subfascia or along angled gable rakes to capture the outer edge of the panels.

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