Roof Sheathing Calculator
Enter your roof’s plan area and pitch, choose OSB or plywood, and the calculator works out the sloped roof area, the number of 4 × 8 sheets with waste, and the material, labor and tear-off cost.
Roof Sheathing Calculator
Calculate how many sheets of plywood or OSB roof sheathing you need, with waste, and estimate material, labor and tear-off costs.
Your results appear here and update as you change the numbers.
How this calculator works
- Roof area = plan area × √(1 + (rise ÷ 12)²).
- Sheets = roof area × (1 + waste) ÷ 32 sq ft per 4 × 8 sheet, rounded up.
- Cost = sheets × price per sheet + sheets × labor per sheet + roof area × tear-off price (if selected), × regional factor.
Worked example
2,000 sq ft of plan area at 6/12 = 2,236 sq ft. With 10% waste: 2,460 ÷ 32 = 76.9 → 77 sheets (70 without waste). At $22 per 1/2 in. OSB sheet and $25 labor per sheet: $1,694 + $1,925 = $3,619 (example prices).
When to get a professional check
Sheathing thickness depends on rafter or truss spacing, span rating and local wind and snow loads (24 in. spacing often calls for 5/8 in. or panel clips). Follow APA span ratings and your code.
Assumptions used — example values, not yet reviewed against current local prices
| Assumption | Value |
|---|---|
| 7/16 in. OSB sheet | $18 /sheet |
| 1/2 in. OSB sheet | $22 /sheet |
| 1/2 in. CDX plywood sheet | $32 /sheet |
| 5/8 in. CDX plywood sheet | $42 /sheet |
| Installation labor | $25 /sheet |
| Old sheathing removal | $1 /sq ft |
Sources and references
Ready for real prices? Learn how to find and vet a local roofer.
How to choose a contractorResults are planning estimates, not quotes. Prices vary by location, contractor and the condition of your roof. Verify sizes and code requirements locally before buying or building.
Frequently asked questions
How many sheets of plywood for a roof?
Roof area ÷ 32, plus 10–15 % waste. A 2,000 sq ft footprint at 6/12 needs about 77 sheets.
OSB or plywood?
OSB is cheaper and standard in dry climates; plywood dries faster and holds nails better after wetting.
What thickness?
It depends on rafter spacing and span rating: 7/16 in. is common at 16 in. on center; 24 in. spacing often needs 5/8 in. or panel clips.
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