Soffit
Calculator

Measure the full perimeter of your house in feet, then measure the overhang width (the distance from the fascia board to the exterior wall) in inches. Multiply the perimeter by the overhang width converted to feet to get the total soffit square footage. Add 10-15% for waste from cuts and fitting. Our soffit calculator does this math instantly — just enter your perimeter and width to get your panel count and cost estimate.

Vinyl soffit is the most popular choice for its low cost ($3-$7/sqft installed), zero maintenance, and resistance to moisture and rot. Aluminum soffit is a close second — slightly more expensive ($5-$9/sqft) but more durable and fire-resistant. Wood soffit offers a classic look ($6-$12/sqft) but requires regular painting and is susceptible to moisture damage. Fiber cement ($7-$14/sqft) is the most durable but also the heaviest and most expensive to install.

Building codes typically require 1 square foot of net free ventilation area for every 150 square feet of attic floor space (or 1:300 if you have a vapor barrier). A balanced soffit vent and ridge vent system is ideal — the soffit vents allow cool air in at the eaves while the ridge vent exhausts hot air at the peak. Use our soffit vent calculator above with the "Mixed" or "Fully Vented" option to estimate your vented panel needs. For ridge vent sizing, consult a roofing professional to ensure balanced airflow.

Soffit width depends on your roof overhang. Most homes have overhangs between 12 and 24 inches, with 16 inches being the most common. The soffit spans the full width of the overhang from the fascia board to the exterior wall. Measure your actual overhang rather than assuming a standard width — older homes may have narrower 6-8 inch overhangs, while craftsman and ranch-style homes often have wider 24-36 inch overhangs.

Soffit installation is considered a moderate DIY project. Vinyl and aluminum soffit panels are lightweight and snap together with a simple channel system. You will need a ladder, tin snips or a circular saw with a fine-tooth blade, a utility knife, a chalk line, and F-channel and J-channel trim. The main challenges are working safely on a ladder and making precise cuts around corners. Professional installation typically adds $2-$4 per square foot to the material cost but ensures proper ventilation and a warranty.

A full soffit replacement project for an average home (160 ft perimeter, 16 inch overhang) costs between $1,400 and $6,700 depending on material. Vinyl is the most affordable at $3-$7 per square foot installed, while fiber cement is the most expensive at $7-$14 per square foot. Additional costs include removing old soffit ($1-$3/sqft), repairing damaged fascia or rafter tails, and painting wood soffit. Get multiple quotes from contractors and use this calculator to verify their material estimates.