TryBuildCalcShed Roof Fascia Calculator (High/Low Eave + Rakes)
Size shed roof fascia instantly.
🕒 Last updated: September 4, 2026
Inputs
ℹ️Hip roofs wrap continuously around the full perimeter with no rake edge — gable and shed roofs have separate eave and rake (sloped gable-end) fascia.
ℹ️The span dimension — governs rake length via the roof's pitch (gable/shed only).
ℹ️Governs the eave length directly (both long walls).
ℹ️Only affects rake length — a hip roof's fascia doesn't depend on pitch at all.
ℹ️Horizontal soffit width along the eaves.
ℹ️Horizontal soffit width along the gable-end rakes — often narrower than the eave overhang.
ℹ️Match this to the actual rafter tail / sub-fascia depth.
Waste
ℹ️Applied to total linear footage/area before dividing into stock boards/panels — covers corner miters and cut waste. 10% is a common estimating default.
Cost
Fascia Boards Needed
5
68.8 ft total (+10% waste), 16 ft 1x8 stock
Soffit Panels Needed
4
55.4 sq ft total (+10% waste), 16"×12ft panels
Fascia Length
Eave length (both sides): 42 ft
Rake length (2 segments): 26.8 ft
Total: 68.8 ft
Soffit Area
Eave soffit (12" overhang): 42 sq ft
Rake soffit (6" overhang): 13.4 sq ft
Total: 55.4 sq ft
Assumptions Used
Standard US light-frame construction. Eave length extends past the building's own end walls by the rake overhang, at both ends, so it physically reaches the rake fascia's outer corner. Rake segment length follows the same rise/run trigonometry as a common rafter's own line length, using the eave overhang (not the rake overhang) as its tail — a barge rafter runs in the same rise/run plane as a common rafter. Soffit area uses the standard simplified "length × overhang width" method used by virtually every fascia/soffit takeoff — the small triangular return area where two differently-sized overhangs meet at a corner is not modeled separately. Waste is applied to total linear footage/area BEFORE dividing into stock boards/panels, not to the final piece count. This calculator computes material quantities only — it does not size attic ventilation (net free area), verify structural fascia/sub-fascia attachment, or account for gutters, downspouts, or fascia-mounted hardware.
Bill of Materials
Main material: 5 pcs + recommended tools
+−
Bill of Materials
Main material: 5 pcs + recommended tools
Computed items reflect your entered dimensions and overhangs; consumables below are general recommendations — actual needs vary by product and site conditions.
For Your Job
Fascia Boards
Soffit Panels
General Tools & Consumables
Fascia hanger / drip edge
Soffit J-channel / F-channel trim
Corner posts / soffit corner caps
Stainless or galvanized fascia nails/screws
Caulk / sealant
Circular saw / miter saw
Tin snips / utility knife
Tape measure
Ladder / scaffold
Safety glasses & work gloves
Diagram simplified for clarity (not to scale) — one eave cross-section shown, rake ends follow the same fascia/soffit detail along the sloped gable edge.
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Fascia & Soffit Calculator.
Shed roof fascia and soffit
A shed roof has 2 eaves (the high wall and the low wall, both the same length) plus 2 rake edges (the sloped sides, following the single continuous roof slope from low to high).
This page defaults to a 12×20 ft shed roof at a 3/12 pitch — edit the inputs above to match your actual addition or lean-to.
Fascia & Soffit Calculator Formula: How Is It Determined?
Fascia length and soffit area, calculated separately per roof edge type and combined into a material takeoff.
Step 1 — Fascia Length
Eave Length = 2 x (Building Length + 2 x Rake Overhang)
Rake Segment Length = Common Rafter Line Length + Eave Overhang Tail (gable/shed only)
Hip Roof: Fascia Length = 2 x (Width + 2xEave OH + Length + 2xEave OH)
Gable/Shed: Fascia Length = Eave Length + (Rake Segments x Rake Segment Length)
Every eave has to physically extend past the building's own end wall by the rake overhang, at both ends, to reach the rake's outer corner and meet it in a clean miter — using just the wall-to-wall building length undercounts it. A hip roof's 4 corner miters meet at the same overhang-extended footprint corners, so its perimeter gets the same 2x-eave-overhang correction on both dimensions. Rake segment length reuses the exact same rise/run trigonometry as a common rafter's own total length (using the EAVE overhang as its tail, since a barge rafter runs in the same rise/run plane as a common rafter) — not a code-table lookup. A gable roof has 4 rake segments (2 per gable end); a shed roof has 2 (each running the full building width).
Step 2 — Soffit Area
Eave Soffit Area = Eave Length x Eave Overhang
Rake Soffit Area = Rake Length x Rake Overhang (gable/shed only)
Hip Roof: Soffit Area = Perimeter x Eave Overhang
The standard simplified "length x overhang width" method — the small triangular return area at each corner isn't modeled separately, the same level of simplification virtually every fascia/soffit takeoff tool uses.
Step 3 — Board & Panel Counts
Padded Fascia Length = Total Fascia Length x (1 + Waste %)
Fascia Boards = ceil(Padded Fascia Length / Stock Length)
Padded Soffit Area = Total Soffit Area x (1 + Waste %)
Soffit Panels = ceil(Padded Soffit Area / Panel Coverage Area)
Waste is applied to the total linear footage/area BEFORE dividing into stock boards/panels — covering corner miters and cut waste — not applied separately to the final piece count.
Worked Example
This example walks through your current inputs above, using the same steps as the Formula section.
Input Values Used
| Input | Value | Why it is used |
|---|---|---|
| Roof type / dimensions | shed / 12×20 ft | Sets eave and rake length |
| Eave / rake overhang | 12" / 6" | Sets soffit width |
| Fascia / soffit stock | 16 ft / 16"×12ft | Sets board/panel count |
Step 1 — Fascia Length
| Calculation | Result |
|---|---|
| Eave length | 42 ft |
| Rake length (2 segments) | 26.8 ft |
| Total fascia length | 68.8 ft |
Step 2 — Soffit Area
| Calculation | Result |
|---|---|
| Eave soffit area | 42 sq ft |
| Rake soffit area | 13.4 sq ft |
| Total soffit area | 55.4 sq ft |
Step 3 — Board & Panel Counts
| Calculation | Result |
|---|---|
| Fascia boards (with 10% waste) | 5 |
| Soffit panels (with 10% waste) | 4 |
Therefore, this 12×20 ft shed roof needs approximately 5 fascia boards (68.8 ft total) and 4 soffit panels (55.4 sq ft total).
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.