Free tool
Enter the rise per 12 inches of run to get the pitch multiplier, slope angle, and true roof area.
A "6/12 pitch" means 6 inches of rise per 12 inches of run.
Multiply the building footprint by the multiplier for the predominant pitch to get true roof surface area.
| Pitch | Multiplier | Angle | Walkable? |
|---|---|---|---|
| 1/12 | ×1.0035 | 4.8° | Walkable |
| 2/12 | ×1.0138 | 9.5° | Walkable |
| 3/12 | ×1.0308 | 14° | Walkable |
| 4/12 | ×1.0541 | 18.4° | Walkable |
| 5/12 | ×1.0833 | 22.6° | Walkable |
| 6/12 | ×1.118 | 26.6° | Walkable |
| 7/12 | ×1.1577 | 30.3° | Steep — caution |
| 8/12 | ×1.2019 | 33.7° | Steep — caution |
| 9/12 | ×1.25 | 36.9° | Steep-slope charge |
| 10/12 | ×1.3017 | 39.8° | Steep-slope charge |
| 11/12 | ×1.3566 | 42.5° | Steep-slope charge |
| 12/12 | ×1.4142 | 45° | Steep-slope charge |
Pitch affects both material quantity and labor. Anything above 8/12 typically needs roof jacks, harnesses, and slower production, which is why most contractors apply a steep-slope charge per square rather than absorbing it. Pricing a 10/12 roof at your 5/12 rate is one of the most common ways a job loses money.