What is this calculator?
Estimate sloped roof area from horizontal area and pitch.
What can you use it for?
Use it for practical planning, conversions, measurement or checking the result described here. Estimate sloped roof area from horizontal area and pitch.
How to use it
- Enter horizontal projected area (m²).
- Enter rise per 12 horizontal units.
- Enter extra material (%).
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
The formula uses the units and definitions shown above. Each input is substituted before the arithmetic is evaluated; the calculated output is rounded for display.
Worked example
Horizontal projected area (m²): 100, Rise per 12 horizontal units: 6, Extra material (%): 10. The result is 122.98373876 m² (result).
Assumptions and limits
Uniform pitch approximation. Complex roofs require measurement.
Frequently asked questions
What inputs does the Roofing Calculator need?
Use horizontal projected area (m²), rise per 12 horizontal units, extra material (%). Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Roofing Calculator?
Uniform pitch approximation. Complex roofs require measurement.