Roof Pitch, Rise, and Run Calculator
Calculate roof pitch angle, rise, run, and rafter length for any roof. Includes common pitch reference guide.
🏗️ Construction📐 Pitch = Rise/Run × 12 (expressed as X:12)
Run (horizontal distance, feet)
Rise (vertical height, feet)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Roof Pitch, Rise, and Run Calculator | Pitch = Rise/Run × 12 (expressed as X:12) | pitch / angle |
Step-by-Step Examples
Example 1
Standard 6:12 Roof
Run 12 ft, rise 6 ft.
- Pitch: 6:12 = 26.6° | Rafter: 13.42 ft
- Common residential pitch, walkable, good drainage
✓ 6:12 / 26.6°
Example 2
Steep 10:12
Run 12 ft, rise 10 ft.
- Pitch: 10:12 = 39.8° | Rafter: 15.62 ft
✓ 10:12 / 39.8°
Example 3
Low 3:12
Run 20 ft, rise 5 ft.
- Pitch: 3:12 = 14.0° | Rafter: 20.6 ft
- Minimum slope for most asphalt shingles
✓ 3:12 / 14.0°
Real-World Applications
Roofers
Calculate rafter length and pitch for any roof.
Homeowners
Understand roof pitch for material selection.
Estimators
Calculate roof area and rafter quantities.
Builders
Quickly reference rafter multipliers for layout.
Common Mistakes to Avoid
⚠️
Minimum slope for roofing material
Asphalt shingles: min 2:12. Metal roofing: as low as 1:12 with proper underlayment. Flat roofs technically have 0.5:12-1:12 slope for drainage.
⚠️
Not calculating rafter length correctly
Rafter length = √(run² + rise²). The rafter multiplier (rafter/run) is useful for quick field calculations: 6:12 pitch multiplier ≈ 1.118.
Frequently Asked Questions
Common roof pitches and their uses? ▾
2:12-4:12: flat to low slope (commercial, contemporary). 4:12-6:12: standard residential (most common). 6:12-9:12: traditional residential. 10:12+: steep (Cape Cod, Victorian). 12:12: 45° — dramatic feature roofs.
How to calculate roof area? ▾
Flat footprint area × pitch multiplier. 6:12 multiplier = 1.118. A 2,000 sq ft footprint with 6:12 pitch = 2,236 sq ft of actual roof area.
What pitch does snow require? ▾
For heavy snow loads: minimum 3:12 to 4:12. Some codes require 6:12+ in high snow areas. Steeper pitch sheds snow better.