Roof pitch guide
Roof pitch calculator and chart
Pitch is rise over a 12-inch run. Use the slope factor to turn a building footprint into roof surface area — or measure a real roof’s pitch by address.
Roof pitch chart
| Pitch | Angle | Slope factor | 2,000 sq ft footprint → | Type |
|---|---|---|---|---|
| 1/12 | 4.8° | 1.003 | 2,006 sq ft | Flat / low slope |
| 2/12 | 9.5° | 1.014 | 2,028 sq ft | Low slope |
| 3/12 | 14.0° | 1.031 | 2,062 sq ft | Low slope |
| 4/12 | 18.4° | 1.054 | 2,108 sq ft | Conventional |
| 5/12 | 22.6° | 1.083 | 2,166 sq ft | Conventional |
| 6/12 | 26.6° | 1.118 | 2,236 sq ft | Conventional |
| 7/12 | 30.3° | 1.158 | 2,316 sq ft | Conventional |
| 8/12 | 33.7° | 1.202 | 2,404 sq ft | Conventional |
| 9/12 | 36.9° | 1.250 | 2,500 sq ft | Steep |
| 10/12 | 39.8° | 1.302 | 2,604 sq ft | Steep |
| 11/12 | 42.5° | 1.357 | 2,714 sq ft | Steep |
| 12/12 | 45.0° | 1.414 | 2,828 sq ft | Steep |
| 13/12 | 47.3° | 1.474 | 2,948 sq ft | Steep |
| 14/12 | 49.4° | 1.537 | 3,074 sq ft | Steep |
| 15/12 | 51.3° | 1.601 | 3,202 sq ft | Steep |
| 16/12 | 53.1° | 1.667 | 3,334 sq ft | Steep |
| 17/12 | 54.8° | 1.734 | 3,468 sq ft | Steep |
| 18/12 | 56.3° | 1.803 | 3,606 sq ft | Steep |
Pitch questions
What does a 6/12 roof pitch mean?
The roof rises 6 inches for every 12 inches of horizontal run — about 26.6°. Its slope factor is 1.118, so a 2,000 sq ft footprint has about 2,236 sq ft of roof surface (before overhangs).
What is the minimum pitch for asphalt shingles?
Most manufacturers allow asphalt shingles down to 2/12 with special underlayment; 4/12 and steeper is standard. Below 2/12 use a low-slope membrane such as TPO, EPDM or modified bitumen.
How do I find my roof pitch without climbing?
Enter the address on RoofTap Measure. We measure the pitch from aerial LiDAR points on the roof — no ladder or pitch gauge needed.
What is a slope factor?
The multiplier that converts horizontal (plan) area into sloped roof surface: √(1 + (pitch/12)²). Multiply the building footprint by it to estimate roof area.