Roof Pitch Calculator
Calculate roof pitch, angle, rafter length, and roof multiplier. Enter rise and run, or choose a common pitch preset below.
Roof Pitch Calculator
Results update instantlyVertical rise per 12 inches of run
Horizontal run (typically 12)
Pitch Diagram
6:12 pitch · 26.6°
Results
Pitch
6:12
Angle
26.57°
Multiplier
1.1180×
Category
Conventional
Rafter Length
13.416 ft
161.00 inches
Per Foot of Run
1.1180 ft
= 13.4164 in
Common Roof Pitch Reference
Click any row to load that pitch.
| Pitch | Angle | Multiplier | Category | % Grade |
|---|---|---|---|---|
| 1:12 | 4.76° | 1.0035 | Flat / Low | 8.3% |
| 2:12 | 9.46° | 1.0138 | Flat / Low | 16.7% |
| 3:12 | 14.04° | 1.0308 | Low Slope | 25.0% |
| 4:12 | 18.43° | 1.0541 | Low Slope | 33.3% |
| 5:12 | 22.62° | 1.0833 | Low Slope | 41.7% |
| 6:12 | 26.57° | 1.1180 | Conventional | 50.0% |
| 7:12 | 30.26° | 1.1577 | Conventional | 58.3% |
| 8:12 | 33.69° | 1.2019 | Conventional | 66.7% |
| 9:12 | 36.87° | 1.2500 | Conventional | 75.0% |
| 10:12 | 39.81° | 1.3017 | Steep | 83.3% |
| 11:12 | 42.51° | 1.3566 | Steep | 91.7% |
| 12:12 | 45.00° | 1.4142 | Steep | 100.0% |
Roof Pitch Categories Explained
Flat / Low
Minimal drainage, requires special roofing materials
Low Slope
Most asphalt shingles OK, good water runoff
Conventional
Most common residential pitch, standard shingles ideal
Steep
Enhanced curb appeal, requires safety equipment to work
Very Steep
Architectural feature, specialized roofing contractors
How to Use
- 1Select a preset (e.g. 6:12) or type custom rise and run
- 2Rise = vertical inches per 12 inches of horizontal run
- 3Enter building span to calculate rafter length
- 4Click any row in the table to load that pitch
Formulas
Angle = atan(rise / run)
Rafter = √(rise² + run²) / run
The roof multiplier tells you how many linear feet of rafter you need per foot of horizontal run.