Use this wall sheathing calculator to estimate how many OSB or plywood sheets you need for exterior walls. It estimates wall area, deducts large openings, adds gable area if needed, applies waste, and converts the result into sheet count.
This is a material planning calculator, not a structural wall bracing, shear wall, wind, seismic, fastening, or code compliance calculator. Final wall sheathing layout still depends on framing, panel orientation, blocked edges, opening layout, local code, and manufacturer instructions.
Estimate your wall sheathing sheets
This is a rough wall-area planning number, not a full flashing/tape takeoff.
How this estimate works
The calculator multiplies wall length by wall height and the number of similar sections. It adds optional gable area, subtracts large openings, adds waste, divides by panel coverage, and adds optional extra sheets for layout cuts or repair uncertainty.
When this wall sheathing calculator is useful
- Estimating OSB or plywood sheets for exterior wall sheathing
- Checking a contractor or material list before ordering panels
- Planning a siding-off wall repair where sheathing may need replacement
- Estimating sheathing for garages, additions, sheds, or small wall sections
- Roughly estimating WRB / housewrap area before doing a separate flashing takeoff
What this calculator does not decide
This calculator does not choose sheathing thickness, panel rating, structural bracing method, fastening schedule, nail spacing, shear wall layout, uplift resistance, or code compliance. Those decisions depend on the building design, local code, manufacturer instructions, and sometimes engineering.
Do not over-deduct every opening
Large windows and doors can be deducted, but small cutouts still create waste. Wall sheathing is not bought by perfect square footage. Corners, seams, staggered layouts, openings, repairs, and damaged sheets all affect the final count.