Use this gable end sheathing calculator to estimate OSB or plywood sheets for triangular gable-end areas. It can calculate the gable triangle alone or include the rectangular wall area below the gable.
This is a material planning calculator, not a structural bracing, wind, gable-end reinforcement, fastening, or code compliance calculator. Gable-end sheathing may have structural requirements depending on roof framing, wall bracing, wind exposure, local code, and manufacturer instructions.
Estimate your gable end sheathing sheets
How this estimate works
The calculator uses the gable triangle formula, adds optional rectangular wall area below the gable, subtracts large openings, adds waste, divides by panel coverage, and adds optional extra sheets for angled cuts or repair uncertainty.
When this gable end sheathing calculator is useful
- Estimating OSB or plywood sheets for triangular gable-end sheathing
- Planning gable repairs after siding removal
- Estimating garage, shed, addition, attic, or house gable sheathing
- Checking a material list before ordering panels
What this calculator does not decide
This calculator does not choose panel thickness, structural gable bracing, fastening schedule, nail spacing, wind resistance, vent flashing, or code compliance. Those decisions depend on the building design, local code, manufacturer instructions, and sometimes engineering.
Do not undercount angled waste
Gable-end sheathing has angled cuts near the roof slope, plus possible vents, attic windows, siding transitions, rake trim, and repair surprises. The triangle math gives the area, but the waste factor is what makes the sheet count more realistic.