Roof Plywood Calculator

Calculate how many sheets of plywood or OSB roof sheathing you need

Get a fast sheet count from your roof area

Quick presets

sq ft

Estimated Materials

60 bundles

17.9 squares • 1,792 sq ft

PRO

Professional Calculator

Extended parameters for precise calculations

sq ft

Estimated Materials

60 bundles

Roof Area

1,792 sq ft

Squares

17.9

Detailed Breakdown

Roof Area1,792 sq ft
With Waste1,971 sq ft
Roofing Squares17.9
Bundles60
How to Use This Calculator
The Roof Plywood Calculator makes it easy to order the right number of sheathing panels for new construction or replacement.

Quick Estimate tab: Enter your total roof area and select a waste factor. The calculator divides by 32 (the area of a 4x8 sheet) and rounds up to give you a sheet count. This is the fastest way to get a ballpark number for a lumber order.

Detailed tab: Choose between OSB and CDX plywood, select the panel thickness, and enter the percentage of decking you need to replace. For re-roofs, most roofers find that 5-15% of the deck has soft spots or rot. The calculator computes the exact number of sheets for your replacement scope, factoring in waste for cuts. Use this tab when you need to budget for decking replacement as part of a re-roof.

Cost Estimate tab: Enter your roof area, material preferences, replacement percentage, and state. The calculator outputs materials cost (per sheet and total) and labor cost for installation. Decking replacement is one of the most common surprise costs in re-roofing — this tab helps you budget accurately before the crew finds soft spots.

The Formula
The roof plywood calculation uses these formulas:

Area to Deck = Total Roof Area × (Replacement% / 100) For 1,700 sq ft with 10% replacement: 1,700 × 0.10 = 170 sq ft

Sheets Needed = (Area to Deck × (1 + Waste%)) / 32 For 170 sq ft with 10% waste: (170 × 1.10) / 32 = 5.84 -> 6 sheets

Material Cost = Sheets × Cost per Sheet 6 sheets × $22 (7/16" OSB) = $132

Labor Cost = Sheets × Labor per Sheet 6 sheets × $55 = $330

Total Installed = Material Cost + Labor Cost $132 + $330 = $462
Example Calculation
Example: Re-Roof with 10% Deck Replacement in Georgia

Linda is having her 1,700 sq ft roof replaced in Atlanta. The roofing crew estimates 10% of the OSB sheathing has water damage and needs replacement.

Step 1: Calculate area to replace Roof area: 1,700 sq ft Replacement percentage: 10% Area to deck: 1,700 × 0.10 = 170 sq ft

Step 2: Calculate sheets needed Area with 10% waste: 170 × 1.10 = 187 sq ft Sheets: 187 / 32 = 5.84 -> 6 sheets of 7/16" OSB

Step 3: Estimate cost
• OSB material: 6 sheets × $22 = $132
• H-clips: 6 × $0.50 = $3
• Materials total: ~$135
• Labor: 6 sheets × $55/sheet = $330
• Total decking replacement: ~$465

This is on top of the shingle replacement cost. For the full deck (all 59 sheets), the cost would be approximately $4,800.

Frequently Asked Questions

How many sheets of plywood do I need for a 1,700 sq ft roof?
A standard 4x8 sheet covers 32 square feet. For a 1,700 sq ft roof with 10% waste, you need: 1,700 × 1.10 / 32 = 58.4, rounded up to 59 sheets. If you are only replacing damaged sections (say 10%), you need about 6 sheets. Always round up since partial sheets cannot be returned easily.
Should I use OSB or plywood for roof sheathing?
Both are code-approved. OSB (7/16") costs $18-26 per sheet in 2026 and is the most widely used roof sheathing. CDX plywood (1/2") costs $30-45 per sheet and handles moisture better — it swells less at edges when wet. In coastal areas, flood zones, or high-humidity climates, plywood is the safer choice. For standard residential re-roofs in dry climates, OSB performs well and saves money.
What thickness of roof sheathing do I need?
For rafters or trusses spaced 24 inches on center (the most common), 7/16" OSB or 15/32" (1/2") plywood is the code minimum. For 16" o.c. spacing, 3/8" is technically minimum but 7/16" is strongly recommended. For heavy snow-load areas or wider rafter spacing, use 5/8" or 3/4". Check your local building code or the APA Span Rating printed on the panel — it shows the maximum rafter spacing.
What are H-clips and do I need them?
H-clips (also called panel-edge clips or plywood clips) are small metal brackets placed between adjacent sheathing panels at the unsupported edge midway between rafters. They prevent differential deflection (one panel sagging more than its neighbor) and provide a small 1/8" expansion gap. Code requires H-clips for 7/16" and 15/32" panels spanning 24" o.c. unless the panel edges land on blocking. You need one clip per unsupported joint, typically 1 clip per sheet.
How much does it cost to replace roof plywood in 2026?
In 2026, the installed cost for roof sheathing replacement averages $75-120 per sheet, including material and labor. Breaking it down: 7/16" OSB runs $18-26/sheet and CDX plywood $30-45/sheet for material. Labor for decking replacement runs $40-70 per sheet because the roofer must remove old material, inspect rafters, and nail the new panel. For a full-deck job on a 1,700 sq ft roof (about 59 sheets), expect $4,400-7,000 total.

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