Soffit and Fascia Calculator
Enter the eave length, the depth of the overhang and the size of your soffit panels and fascia boards and get the soffit panels and fascia boards to buy, each rounded up once, with vented panels when you enter the net free area you need and the area of one panel. The working is shown for an example.
Estimates for planning, not professional advice. Read the full notice.
Example: a soffit along one eave
8 soffit panels
- Soffit area 80 ft²
- Fascia boards 4 fascia boards
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Soffit panels | soffit panels | 8 |
| Fascia boards | fascia boards | 4 |
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Worked example: a soffit along one eave
Show the working
- Rows of panels across the depth: the depth over the cover width, rounded up 2 ft ÷ 1 ft = 2 rows
- Panels in one row: the eave length over the panel length, rounded up (the leftover of a panel is not carried to the next row) 40 ft ÷ 12 ft = 4 panels
- Panels: the panels in one row times the rows 4 panels × 2 rows = 8 soffit panels
- Fascia: the eave length over the board length, rounded up once 40 ft ÷ 12 ft = 4 fascia boards
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|
Feet and inches, like 12' 6"
Soffit panels by overhang depth
Soffit area and panels for the example eave, by the depth of the overhang, with panels running along the eave
| Overhang depth | Soffit area | Panels |
|---|---|---|
| 12 in | 40 ft² | 4 soffit panels |
| 18 in | 60 ft² | 8 soffit panels |
| 24 in | 80 ft² | 8 soffit panels |
| 30 in | 100 ft² | 12 soffit panels |
| 36 in | 120 ft² | 12 soffit panels |
Each row is worked out on its own for the example eave length, cover width and panel length, rounded up once.
Questions
How many square feet does one box of soffit cover?
It depends on the panel size on your own label. Enter the cover width and the panel length and the calculator counts panels; the soffit area it shows is the eave length times the depth.
What do F channel and J channel count here?
This calculator counts soffit panels, fascia boards and, when you ask for them, vented panels. Channels for the edges are not counted; the siding calculator counts J-channel for openings and rakes.