Roof Sheathing Calculator
Estimate roof sheathing sheets from total roof area, sheet size, and waste percentage. Use it to estimate sheet counts and reduce material shortages when ordering sheathing.
Inputs
Enter total roof surface area (all planes). If you only know footprint, use a pitch multiplier first.
Results
Assumptions
- Sheathing is estimated by area only and does not model cut layout.
- Waste covers cuts, hips/valleys, and mistakes.
- Results are rounded up for ordering.
Example
A 1,600 sq ft roof using 4x8 sheets with 10% waste needs about 56 sheets.
How the Roof Sheathing Calculator Works
We multiply roof area by your waste factor, then divide by sheet coverage to get total sheets needed. Results are rounded up for ordering.
FAQ
OSB vs plywood—does it change sheet count?
No. Sheet count is based on area, so OSB and plywood use the same calculation for a given sheet size. For area checks, use the roofing squares calculator.
Should I use roof footprint or roof surface area?
Use roof surface area. Footprint ignores pitch and will undercount on steeper roofs.
How much waste should I add?
Most roofs use 10–15% waste for cuts, hips/valleys, and layout loss. Simple roofs can stay closer to 10%. For a full materials checklist, see the roofing calculators guide.
What sheet thickness do I need?
Thickness depends on span and local requirements. Common ranges are 7/16" to 5/8", but check local code or roof specs.
Does this include fascia/trim?
No. This calculator estimates sheathing sheets only, not trim or fascia.
Related Roofing Tools
New to Roofing Calculations?
Start with our comprehensive Roofing Calculator Guide to understand roofing squares, bundles, pitch multipliers, and material estimates before ordering.