Roof Pitch Diagram
Pitch Ratio
Ratio = Rise ÷ Run
Angle (Degrees)
θ = arctan(Rise ÷ Run) × (180/π)
Percentage
% = (Rise ÷ Run) × 100
| Ratio | Angle | Use |
|---|---|---|
| 4:12 | 18.4° | Minimum for shingles |
| 6:12 | 26.6° | Standard residential |
| 8:12 | 33.7° | Traditional look |
| 10:12 | 39.8° | Victorian style |
| 12:12 | 45.0° | A-frame/steep |
Disclaimer
Results are estimates. Actual roof pitch may vary due to construction tolerances and design adjustments. Always verify measurements on-site and consult with a professional roofer or engineer for construction projects.
Roof pitch, also known as roof slope, is a measure of how steep a roof is. It describes the vertical rise of the roof relative to its horizontal run. Understanding roof pitch is essential for roofing projects as it affects material selection, drainage, structural requirements, and overall aesthetics of a building.
Roof pitch is commonly expressed in three ways: as a ratio (e.g., 6:12, meaning 6 inches of rise for every 12 inches of run), as an angle in degrees, or as a percentage. The ratio format is most commonly used in the United States construction industry, while degrees and percentages are more universal and often used in engineering and international contexts.
Rise is the vertical distance from the top of the roof to the bottom edge (eave). It represents how much the roof climbs vertically. The rise is measured perpendicular to the ground, straight up and down.
Run is the horizontal distance from the edge of the roof to the point directly below the peak (or the point where rise is measured). It's important to note that run is not the same as the actual length of the roof surface (which is longer due to the slope).
For a standard gable roof, the total span (width of the building) equals twice the run, as the run is measured from the center peak to the edge on one side only.
Material Selection
Different roofing materials have minimum pitch requirements. Asphalt shingles typically require at least 4:12 pitch, while metal roofing can work on lower slopes. Flat roofs need special membrane materials.
Water Drainage
Steeper roofs shed water and snow more effectively. In areas with heavy rainfall or snowfall, adequate pitch is crucial to prevent water pooling, leaks, and structural damage.
Structural Requirements
Steeper roofs require stronger framing to resist wind uplift and support workers during installation. They also create more attic space but require more roofing materials.
Aesthetics & Style
Roof pitch significantly impacts a building's appearance. Colonial and Victorian homes typically have steeper pitches, while modern and ranch-style homes often feature lower slopes.