Roof Calculator
Roofing material by dimensions.
Tip: Roof pitch affects the area — a steeply pitched roof has a larger area.
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About this digital tool
The roof calculator estimates the real area of the roof and the amount of covering material, such as ceramic tiles, concrete tiles or sheet metal, from the building's dimensions and the pitch angle. Enter the length, width and the angle in degrees and choose the type of material.
A pitched roof has a larger area than the view from above. The tool uses the formula area = (length × width) ÷ cos(angle), then multiplies by the pieces per m² (15 for ceramic tile, 10 for concrete tile, 1 for sheet metal) and adds 10% spare. It also gives the building's perimeter. It is useful for builders and for owners who want an estimate before asking for a quote.
How to use
- Choose the type of covering: ceramic tile, concrete tile or sheet metal.
- Enter the length and width of the building in metres.
- Set the roof pitch angle in degrees.
- Read the roof area, the number of pieces (+10%) and the perimeter.
Frequently asked questions
How many tiles are needed per m²?
It depends on the size: standard tiles ~12–15 pieces/m². Sheet metal: ~1 sheet per 2–3 m² depending on width.
How is the area of a pitched roof calculated?
The plan area is divided by the cosine of the pitch angle. For a 10 × 8 m building with a 30° angle, the roof area comes to about 92 m², not 80 m². The tool calculates this automatically.
What pitch angle should the roof have?
The angle depends on the material, the climate and the architect's design. The tool accepts angles between 0° and 90° (excluding both ends), so you can compare several options to see how the amount of material changes.
Is the material spare included in the result?
Yes, the amount of material includes 10% more for cuts, breakages and the roof edges. It is also written on the label of the result row.