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Metal Roof Calculator

A metal roof calculator works out how many metal roofing panels and screws you need, scaling your footprint up by the pitch and dividing by each panel's coverage width and length. It's built for exposed-fastener panels (the common ribbed/corrugated DIY type).

Your measurements

Result

The trap with metal is coverage width: a 36-inch sheet only covers about 34-35 inches once it laps the next panel. This uses coverage width so you don't come up a panel short.

How it is calculated

Roof area = footprint × √(1 + (rise/12)²). Panels = roof area × waste multiplier ÷ (coverage width × panel length). Screw estimate ≈ 80 per square for exposed-fastener panels with screws at the ribs. Standing-seam uses concealed clips instead of field screws.

Steps

Enter your footprint and pitch, or the actual roof area.
Enter the panel coverage width (not the full sheet width).
Enter the panel length you'll order.
Add a waste allowance for cuts and laps.
Read the panel count and screw estimate.

Worked example

An 1,800 sq ft roof with 36 in × 12 ft panels (3 ft coverage) needs about 55 panels with 10% waste, and ~1,440 screws.

Common questions

How many metal roofing panels do I need?

Roof area divided by each panel's coverage area (coverage width × length), plus waste. The calculator does it from your footprint and pitch.

What's coverage width vs panel width?

Coverage width is the exposed face after panels overlap — an inch or two less than the full sheet. Always estimate on coverage width.

How many screws per panel?

Roughly 80 screws per square (100 sq ft) for exposed-fastener panels — more on the eaves, ridges and laps.

Can I use this for standing seam?

Use it for panel count and footage; standing seam is fastened with hidden clips, so ignore the screw figure.