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Metal Roofing Calculator

Find how many metal roofing panels a roof needs from its footprint, pitch and the panel size, with the cost.

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

Enter the footprint, the pitch and the panel size.

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.
Eave to ridge, or as sold.
Exposed width after the side lap.
For waste, cuts or compaction; for example 10.
For the cost.
Result
Panels
27 panels
Roof area
1,264.91 sq ft (12.65 squares)
Each panel covers
48 sq ft

You need about 27 panels.

Show the working
  1. panels = roof area ÷ panel coverage, rounded up

How to use it

Enter the footprint, the pitch and the panel size.

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

Key facts

panels = roof area ÷ (panel length × coverage width), rounded up

Panels

Exposed-fastener panels are commonly 26 or 36 in wide; standing-seam pans 12–18 in.

Questions

How many 36 in × 16 ft panels for a 40 × 30 ft footprint at 4/12?

27 panels before waste.

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

Formulas

panels = roof area ÷ (panel length × coverage width), 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