Metal roofing calculator

Estimate outputs: Roof panels, Total board length, Area. Adjust Slope length, Eave length, Effective panel width to match your project.

Inputs and units

Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.

Parameter	Example input
Slope length	5.5 m
Eave length	10 m
Effective panel width	1 m
Waste allowance	8 %

Formula and assumptions

Roof panels
ceil(ceil(Eave length / Effective panel width) × (1 + Waste allowance / 100))

Total board length
Roof panels × Slope length

ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.

Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.

Roof calculations assume a simple rectangular surface or equal pitch slopes. Include overhangs in the entered plan dimensions; check overlaps and effective coverage.

Worked example

Sample values are examples, not product specifications. Run the calculation again with your own measurements.

Result	Calculation
Roof panels	11
Total board length	60.5 m
Area	60.5 m²

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