Roof deck sheet estimator

Roof Sheathing Calculator

Estimate roof sheathing sheets from roof length, run, pitch, roof planes, sheet coverage, and waste. Use it before shingle, underlayment, or roof framing takeoffs when the question is how many OSB or plywood sheets to order.

Units

Roof length along ridge (ft)Horizontal run per plane (ft)Eave overhang (ft)Roof pitch (in / 12)Roof planes Sheet coverage (ft²)Waste / cuts (%)Cost per sheet ($)

Sheets to buy

Order area

Squares / measured area

Rough cost

Roof sheathing counts do not choose panel rating

This is a material count only. Panel thickness, span rating, clips, nailing schedule, diaphragm design, ventilation, roof geometry, and local code must be checked before sheathing a roof.

Android App

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Plywood Sheathing Calculator

Estimate general wall, floor, or roof sheet goods from flat area.

Roof Framing Calculator

Count rafters and ridge boards before roof sheathing.

Roof Underlayment Calculator

Estimate underlayment rolls after the roof deck area is known.

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Roof sheathing formula

Slope length = sqrt((run + overhang)² + rise²)

Rise = (run + overhang) × pitch ÷ 12

Measured area = slope length × roof length × roof planes

Sheets = measured area × (1 + waste %) ÷ sheet coverage

Sample takeoff

A 40 ft roof length, 12 ft run, 1 ft overhang, 6/12 pitch, two planes, and 10% waste needs about 40 sheets of 4×8 roof sheathing.A 12 m roof length, 3.6 m run, 0.3 m overhang, 6/12 pitch, two planes, and 10% waste needs about 40 sheets at 2.88 m² coverage.

Roof Sheathing Calculator FAQ

How do I calculate roof sheathing sheets?+

Find the sloped roof area from run, pitch, roof length, and plane count. Add waste, then divide by sheet coverage.Find the sloped roof area from run, pitch, roof length, and plane count. Add waste, then divide by sheet coverage.

Does this pick OSB thickness or nail spacing?+

No. It only counts sheets. Panel thickness, span rating, fastener schedule, clips, and local code are separate checks.No. It only counts sheets. Panel thickness, span rating, fastener schedule, clips, and local code are separate checks.

Can I use it for gable roofs?+

Yes for a simple gable roof with matching planes. Enter the roof length along the ridge, the horizontal run per plane, and two roof planes.Yes for a simple gable roof with matching planes. Enter the roof length along the ridge, the horizontal run per plane, and two roof planes.