Roof measurement
Roof area from footprint and pitch
Convert footprint to sloped roof area. Roof cannot be safely accessed; footprint and pitch are available.
Try the calculation
Use footprint dimensions and roof pitch for a simple section.
Adjustable example. Change these illustrative inputs to match your task, then recalculate. Reset restores the example and its result.
Understand the result
How this calculation works
This tool turns a rectangular footprint into sloped surface area using one pitch.
Steps
- Enter footprint length, footprint width and the rise portion of the pitch.
- Keep the pitch tied to the section being estimated.
The form starts with the worked example below. Change its values and selections to match your task; Reset restores the example.
Formula
A = length × width × √(1 + (pitch ÷ 12)²).
Variables and units
- Footprint length (ft)
- Required. Use a positive value. Starting example: 40. Replace it for your task.
- Footprint width (ft)
- Required. Use a positive value. Starting example: 30. Replace it for your task.
- Pitch rise (in per 12 in)
- Required. Zero is accepted. Starting example: 6. Replace it for your task.
What the result means
It is a planning area for a simple rectangular section. Valleys, hips, dormers and separate pitches need measured planes or separate sections.
Worked example
Inputs: Footprint length = 40; Footprint width = 30; Pitch rise = 6.
Calculation: For 40 ft × 30 ft at 6:12: 1,200 × √1.25 = 1,341.64 sq ft.
Result: 1,341.64 sq ft.
Frequently asked questions
Does it calculate a complex roof?
No. Split complex geometry into measured planes or use the applicable shape pages.
What does 6:12 mean here?
Six inches of rise for each 12 inches of horizontal run.
Should I add waste here?
Use a material quantity tool so the waste assumption remains visible.