Complete reference for roof pitch conversions. Find the pitch ratio, slope in degrees, area multiplier for materials, and rafter length factor for any standard roof pitch.
Roof pitch is expressed as rise over run — a 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. The first number is the rise, and the run is always 12. Steeper pitches shed water and snow faster but use more material and are harder to work on.
| Pitch | Degrees | Rise/ft | Multiplier |
|---|---|---|---|
| 1/12 | 4.8° | 1" | 1.003 |
| 2/12 | 9.5° | 2" | 1.014 |
| 3/12 | 14.0° | 3" | 1.031 |
| 4/12 | 18.4° | 4" | 1.054 |
| 5/12 | 22.6° | 5" | 1.083 |
| 6/12 | 26.6° | 6" | 1.118 |
| 7/12 | 30.3° | 7" | 1.158 |
| 8/12 | 33.7° | 8" | 1.202 |
| 9/12 | 36.9° | 9" | 1.250 |
| 10/12 | 39.8° | 10" | 1.302 |
| 11/12 | 42.5° | 11" | 1.357 |
| 12/12 | 45.0° | 12" | 1.414 |
| 14/12 | 49.4° | 14" | 1.537 |
| 16/12 | 53.1° | 16" | 1.667 |
4/12–7/12 rows highlighted — the most common residential pitch range.
The area multiplier converts flat (plan-view) area to actual roof surface area. Flat area × multiplier = true roof area for ordering materials.
Example: 30 × 40 ft ranch house, 6/12 pitch
Flat area = 1,200 sq ft × 1.118 = 1,342 sq ft actual roof surface
The rafter factor gives rafter length per foot of horizontal run. For a 6/12 roof with 15 ft of run: 15 × 1.118 = 16.77 ft rafter length (before adding overhang).
Need to calculate roofing materials? Use our Roofing Calculator.
| Pitch Range | Suitable Materials |
|---|---|
| 0/12 – 2/12 | Built-up roofing (BUR), single-ply membrane (TPO/EPDM), modified bitumen |
| 2/12 – 4/12 | Metal panels, rolled roofing (with additional underlayment) |
| 4/12 – 8/12 | Asphalt shingles (most common range), metal panels, wood shakes |
| 8/12 – 12/12 | Asphalt shingles, slate, clay/concrete tile, cedar shakes |
| 12/12+ | Slate, tile, specialty metal (requires extra fastening) |
Note: Most asphalt shingle manufacturers require a minimum 4/12 pitch. Some allow 2/12 with double underlayment. Always check manufacturer specifications.
| Pitch | Walkability |
|---|---|
| 0/12 – 6/12 | Walkable — most people comfortable without equipment |
| 7/12 – 9/12 | Caution — roof jacks and non-slip boots recommended |
| 10/12 – 12/12 | Steep — roof jacks, harness, and toe boards required |
| 12/12+ | Extreme — scaffolding or specialized equipment needed |
4/12 to 6/12 is the most common range for residential construction. A 4/12 pitch is the minimum for standard asphalt shingles without special installation requirements.
Place a level horizontally against the roof with one end touching the surface. Measure 12 inches along the level from the roof surface, then measure straight down from that point to the roof. That vertical measurement is your rise — giving you rise/12 pitch.
The roof rises 6 inches vertically for every 12 inches of horizontal distance. This equals a 26.6° angle from horizontal.
Higher pitch = more surface area = more materials. A 12/12 pitch roof has 41% more surface area than a flat roof over the same footprint. Use the multiplier column to calculate exactly how much more material you need.
Most manufacturers require 4/12 minimum. Some allow 2/12 with double-layer underlayment and special installation. Below 2/12, use membrane or built-up roofing instead.
Degrees = arctan(rise ÷ 12). Or use the table above — a 6/12 pitch equals 26.6 degrees.