Roof Pitch Calculator
Convert roof rise and horizontal run into x:12 pitch, degrees and an area multiplier.
Formula
x = 12r/d; angle = atan(r/d); area multiplier = √(1+(r/d)²).
Roof rise: 6 ft · Horizontal run: 12 ft · Rise per 12 units of run ≈ 12×(6 ft × 0.3048 m/ft)÷(12 ft × 0.3048 m/ft) · Roof angle ≈ atan((6 ft × 0.3048 m/ft)÷(12 ft × 0.3048 m/ft))×180÷pi · Percent slope ≈ 100×(6 ft × 0.3048 m/ft)÷(12 ft × 0.3048 m/ft) · Area multiplier ≈ sqrt(1+((6 ft × 0.3048 m/ft)÷(12 ft × 0.3048 m/ft))^2)
How to use
- Measure vertical rise and horizontal run.
- Choose the measurement units.
- Read x for x:12, angle and area multiplier.
Examples
- Rise 9 and run 12 give 9:12 and a 1.25 area multiplier.
Frequently asked questions
What does 6:12 mean?
The roof rises 6 units for every 12 horizontal units.
Is pitch measured over the full span?
This tool uses rise/run, the common x:12 convention, not rise/full span.
Does this approve roofing materials?
No. Check manufacturer limits and applicable design requirements.
Sources
Updated: