Soffit Calculator
Soffit panels, fascia and vent area for your eaves.
Enter your values
Enter the total eave run in ft.
Enter the overhang width in in.
Enter the attic floor area in sq ft.
per piece
Enter the price per panel in $.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Soffit area
- 180 sq ft
- Panels needed
- 12
- Fascia board
- 120 linear ft
- Total vent area required
- 768 sq in
- Soffit intake needed
- 384 sq in (half at the eaves)
- Material cost
- $168.00
Quick answer
Soffit area = eave run × overhang width; building code wants 1 sq ft of net free vent area per 300 sq ft of attic, split half low and half high.
soffit area = run × overhang
At a glance
| What it does | Soffit panels, fascia and vent area for your eaves. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Total eave run, Overhang width, Attic floor area, Panel coverage, Price per panel |
| Main output | Soffit area |
| Formula | soffit area = run × overhang |
| Cost | Free — no sign-up, no download |
How to use the Soffit Calculator
- 1Measure the total eave run around the house.
- 2Enter the overhang width in inches.
- 3Add the attic floor area to size the ventilation.
Inputs explained
- Total eave run(ft)
- Enter the total eave run in ft.
- Overhang width(in)
- Enter the overhang width in in.
- Attic floor area(sq ft)
- Enter the attic floor area in sq ft.
- Panel coverage(sq ft)
- per piece
- Price per panel($)
- Enter the price per panel in $.
Worked example
Using the values the calculator loads with:
Inputs
- Total eave run120 ft
- Overhang width18 in
- Attic floor area1600 sq ft
- Panel coverage16 sq ft
- Price per panel14 $
Results
- Soffit area180 sq ft
- Panels needed12
- Fascia board120 linear ft
- Total vent area required768 sq in
- Soffit intake needed384 sq in (half at the eaves)
- Material cost$168.00
Frequently asked questions
How much soffit venting do I need?
1 sq ft of net free area per 300 sq ft of attic, with half at the soffit and half at the ridge.
Is vented soffit needed everywhere?
Continuous vented panels work best, but alternating vented and solid panels is acceptable if the total net free area is met.
What do I need to enter into the Soffit Calculator?
Just 5 values: total eave run, overhang width, attic floor area, panel coverage, price per panel. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Soffit Calculator work out the answer?
Soffit area = eave run × overhang width; building code wants 1 sq ft of net free vent area per 300 sq ft of attic, split half low and half high. It applies the formula soffit area = run × overhang and shows the working so you can check each step by hand.
Is the Soffit Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.