Skip to content
RK Calculator
Menu

Roof Sheathing Calculator

Find how many plywood or OSB sheets sheathe a roof, from the footprint and pitch or the roof's area.

Change the values and press Calculate to work out your own figures.

From the footprint

Enter the footprint and the pitch.

Size of this dimension.
Size of this dimension.
Rise in inches per 12 in of run (4 for a 4/12 roof), or an angle.
x/12 or degrees.
Width × length.
For waste, cuts or compaction; for example 10.
For the cost.
Result
Sheets
53 sheets
Area
1,677.05 sq ft (155.8 m²)
Sheet
4 × 8 ft (32 sq ft)

You need 53 sheets.

Show the working
  1. sheets = area ÷ sheet area, rounded up

From the roof's area

Enter the roof's surface area.

The area to fill.
Width × length.
For waste, cuts or compaction; for example 10.
For the cost.
Result
Sheets
94 sheets
Area
3,000 sq ft (278.71 m²)
Sheet
4 × 8 ft (32 sq ft)

You need 94 sheets.

Show the working
  1. sheets = area ÷ sheet area, rounded up

How to use it

Enter the footprint and the pitch. Enter the roof's surface area.

Lengths can be decimals, fractions or tape entries such as 12' 6 1/2" (in feet or inches). Prices are optional.

Key facts

sheets = roof area ÷ sheet area, rounded up

Thickness

7/16 in OSB or 1/2 in plywood is common on rafters 24 in apart; check the span rating and your code.

Questions

How many sheets for 3,000 sq ft of roof?

94 sheets of 4 × 8.

Reviewed by RK Calculator Team. Updated 2026-09-26.

Formulas

sheets = roof area ÷ sheet area, rounded up

Sources

Limitations

  • Material densities are typical values (the midpoint of the commonly published range); real loads vary with moisture, grading and compaction, so check with your supplier or type in their density.
  • Tank results are the geometric volume; real tanks have wall thickness and fittings.

Formula version 0.1.0Reviewed