Free visual roofing tools
Roof Surface Area Calculator
See how pitch turns a horizontal roof projection into sloped surface area.
Net sloped roof surface
2,236.07 sq ft- Horizontal projected area
- 2,000 sq ft
- Net sloped roof area
- 2,236.07 sq ft
- Net roofing squares
- 22.3607 squares
No waste included. Projected area must include relevant overhangs. Assumes one uniform pitch; calculate different facet pitches separately and sum their sloped areas.
Display rounded to 2–4 decimals; calculations keep full precision. Whole purchase units round up.
Sloped area = projected area × √(1 + (rise ÷ run)²)
Educational planning tool · Example values are not measurements of your property.
From a flat projection to a sloped surface
Sloped area = horizontal projected area × √(1 + (rise ÷ run)²). Rise and run are converted to the same unit first. One square meter is 10.7639104167 square feet.
A worked example
For a synthetic 2,000 sq ft roof projection at 6/12 pitch, the multiplier is approximately 1.1180. The sloped roof area is approximately 2,236.07 sq ft, or 22.3607 roofing squares, before waste.
| Projected area | Pitch | Sloped area |
|---|---|---|
| 2,000 sq ft | 6/12 | 2,236.07 sq ft |
What to include
Use the horizontal roof projection, including overhangs. This tool assumes a uniform pitch. For a roof with several pitches, calculate each facet separately and sum the sloped areas. Do not apply pitch to an area already measured along the surface.