Calculator
Formula Used
This calculator uses standard right-triangle geometry for gable rise and a spacing-based stud layout.
Gable Rise
run = (building width ÷ 2) + optional overhang
gable rise = run × (pitch rise ÷ 12)
total ridge height = wall height + gable rise
Sheathing Area
rectangle = width × wall height
triangle = 0.5 × width × gable rise
net = (rectangle + triangle − openings) × (1 + waste%)
Stud Layout (Approximation)
Studs are placed along the gable width using your spacing. For a stud at position x, extra gable height above the wall is estimated using symmetry:
extra(x) = min(x, width − x) × (pitch rise ÷ 12)
stud length(x) = wall height + extra(x)
How to Use
- Select your preferred unit system and units for length and spacing.
- Enter building width, wall height, overhang, and roof pitch rise per 12.
- Set stud spacing, plate counts, lumber size, and a waste factor.
- Enter sheet size and optional openings to subtract from sheathing.
- Click Calculate to view results above the form.
- Use Download CSV or Download PDF to export results.
Example Data Table
| Scenario | Width | Wall height | Pitch | Spacing | Gable rise | Sheets (4×8) |
|---|---|---|---|---|---|---|
| Small garage | 20 ft | 8 ft | 6:12 | 16 in | 5.00 ft | 10 |
| Workshop | 24 ft | 9 ft | 8:12 | 16 in | 8.00 ft | 14 |
| Barn end | 32 ft | 10 ft | 5:12 | 24 in | 6.67 ft | 18 |
Examples are illustrative and may differ from site conditions.
Accurate gable estimates help safer builds and cleaner budgets.