Metal Roofing Calculator

Calculate how many metal roofing sheets or panels you need from the roof area and the panel coverage width.

Part of:Roofing hub
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How to Use This Calculator

How to Use

  1. Enter the roof length along the eaves and the slope (rafter) length from eaves to ridge for one slope.
  2. Enter the cover width of your sheet — this is the effective width after the side overlap, not the full sheet width.
  3. If your slope is longer than one sheet, enter the sheet length and end lap so we can work out rows up the roof.

Cover width vs sheet width

Metal roofing sheets overlap at the sides, so the effective cover width is less than the full sheet width. Always use the cover width quoted by the manufacturer for an accurate sheet count.

Tips

The result is per slope. For a simple gable roof with two equal slopes, double it. Add 10% waste for cuts around hips, valleys and openings, plus ridge, eaves and flashing trims which are ordered separately.

Common Questions

What is the cover width of a metal roof sheet?

It is the effective width once sheets overlap at the sides, which is less than the full sheet width. Manufacturers quote both, so always use the cover width for counting.

How do I count sheets for a long slope?

If the slope is longer than one sheet, sheets overlap end to end. Enter the sheet length and end lap and the calculator works out how many rows you need up the roof.

Does this include both sides of the roof?

The main figure is per slope. We also show the total for a simple gable roof with two equal slopes, which is double.

How much waste should I allow?

Around 10 percent is sensible for cuts at hips, valleys, verges and openings. Complex roofs may need more.

Are flashings and trims included?

No. Ridge, eaves, verge and valley flashings, plus fixings and sealing washers, are ordered separately to suit your roof profile.

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