About the Gable Roof Calculator
Area, rafter length, ridge height and gable end area for a two-slope gable roof.
Also known as: gable end calculator, pitched roof calculator, two slope roof.
How to use this calculator
- Enter building length, building width, roof pitch, overhang.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
area = 2 × (run + overhang) ÷ cos(pitch) × length
Worked example
Using the values pre-filled in the calculator above:
- Building length = 12 m
- Building width = 8 m
- Roof pitch = 35 °
- Overhang = 0.4 m
the calculator returns:
- Total roof area: 137.508 m²
- Rafter length: 5.3714 m
- Ridge height above the wall plate: 2.801 m
- Ridge length: 12.8 m