Roof shingle calculator

Estimate outputs: Area, Area with allowance, Whole bundles. Adjust Length, Width, Roof slope factor 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
Length	10 m
Width	8 m
Roof slope factor	1.15
Coverage per bundle	3 m²
Waste allowance	10 %

Formula and assumptions

Area
Length × Width × Roof slope factor

Whole bundles
ceil(Area × (1 + Waste allowance / 100) / Coverage per bundle)

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
Area	92 m²
Area with allowance	101.2 m²
Whole bundles	34

Related calculators

Related tools use separate measurements. Check their inputs before transferring quantities.