Calculate soffit square footage and panel quantity from total eave length, soffit depth, panel coverage and waste for a practical exterior material estimate.
Enter your measurements and material details.
Measure only the eaves that actually receive soffit and separate porches or unusually deep overhangs if their dimensions differ.
Soffit material is usually planned from the horizontal underside of the roof overhang. The key measurements are the total eave length and average soffit depth. This tool converts those dimensions into square footage and then into pieces or panels using the coverage you enter.
Walk the perimeter and total the eave lengths that will be covered. Measure the horizontal depth from the wall or fascia line to the outer edge of the soffit. If gables, porches or bump-outs have different depths, calculate them separately and add the quantities.
Multiply total eave length in feet by soffit depth in feet.
Only if those areas are actually being covered with soffit material.
Around 10% is a common planning allowance for straightforward runs; complex roofs can need more.
No. Fascia boards or metal fascia are separate linear-foot materials.
Yes, as long as you enter the effective square-foot coverage for the selected panel or piece.
Using the example inputs shown in the calculator — Total soffit/eave length (ft) = 120, Soffit depth (in) = 18, Coverage per panel/piece (sq ft) = 12, Waste allowance (%) = 10 — the result is 198 sq ft. This demonstrates the formula with a complete set of numbers rather than a hidden assumption.
The result breakdown also shows Net soffit area: 180 sq ft; Panels / pieces: 17. Replace the example values with field measurements and the exact product coverage, yield or package size you plan to buy.
For this soffit calculator, the inputs with the greatest practical effect are total soffit/eave length, soffit depth and coverage per panel/piece. Recalculate when any of those change; do not reuse a result from a different room, run, layer depth or product specification.
A useful soffit estimate begins with dimensions taken from the actual project. Small measurement errors can become significant when they are repeated across many boards, joints, courses, bags or rolls. Record the dimensions you used and keep net geometry separate from the purchase allowance so the result can be checked later.
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