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Roofing Calculators

Roof Area Calculator

Actual roof surface area from the building footprint and pitch, for gable or hip roofs.

Enter values

Results update as you type.

Result

Roof surface area

125.123 m²

Plan area including overhang
108.36 m²
Slope multiplier
1.1547
In square feet
1,346.8
Roofing squares (100 ft²)
13.47
Ridge length
12.6 m
Eaves length
25.2 m

About the Roof Area Calculator

Actual roof surface area from the building footprint and pitch, for gable or hip roofs.

Also known as: roof square meters, roof surface area, roof size calculator, roofing area.

How to use this calculator

  1. Enter roof type, building length, building width, eaves overhang and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

roof area = plan area ÷ cos(pitch)

Worked example

Using the values pre-filled in the calculator above:

  • Roof type: Gable (two slopes)
  • Building length = 12 m
  • Building width = 8 m
  • Roof pitch = 30 °
  • Eaves overhang = 0.3 m

the calculator returns:

  • Roof surface area: 125.123 m²
  • Plan area including overhang: 108.36 m²
  • Slope multiplier: 1.1547
  • In square feet: 1,346.8