Roof pitch calculator — angle, multiplier & roof area
Roof pitch is rise over a 12-inch run: measure any rise/run pair and this converts it to standard x/12 pitch, degrees, and the pitch multiplier that turns your home’s footprint into true roof area — the number a shingle order or a roofing quote is built on.
Your pitch
6/12 is the most common residential pitch — walkable with care, and standard for every shingle line.
Pitch multiplier table (1/12 – 12/12)
| Pitch | Angle | Multiplier | Notes |
|---|---|---|---|
| 1/12 | 4.8° | 1.003 | Low slope — membrane/special shingles |
| 2/12 | 9.5° | 1.014 | Low slope — check shingle minimums |
| 3/12 | 14.0° | 1.031 | Minimum for most shingles |
| 4/12 | 18.4° | 1.054 | Common on ranches; walkable |
| 5/12 | 22.6° | 1.083 | Common; walkable |
| 6/12 | 26.6° | 1.118 | Most common residential pitch |
| 7/12 | 30.3° | 1.158 | Upper end of comfortably walkable |
| 8/12 | 33.7° | 1.202 | Steep — staging/harness territory |
| 9/12 | 36.9° | 1.250 | Steep |
| 10/12 | 39.8° | 1.302 | Steep — adds labor cost |
| 11/12 | 42.5° | 1.357 | Very steep |
| 12/12 | 45.0° | 1.414 | Very steep — 45 degrees |
How this calculator works
Pitch: rise ÷ run, normalized to a 12-inch run. Angle: arctan(rise ÷ run). Slope %: rise ÷ run × 100. Multiplier: √(1 + (rise/run)²) — the ratio of true rafter-line length to horizontal run, which is also the ratio of roof surface to footprint on a uniform-pitch roof. Complex roofs (intersecting hips, dormers) run slightly higher than the multiplier alone suggests — that’s part of what the 10% waste factor in our roof cost calculator covers.
Common questions
What does a 6/12 roof pitch mean?
The roof rises 6 inches for every 12 inches of horizontal run — about 26.6°. It’s the most common residential pitch: steep enough to shed water well, shallow enough to walk with care.
How do I measure my roof pitch?
From the attic: hold a level horizontally against a rafter, measure 12 in along the level, then measure straight down to the rafter — that vertical distance is your pitch. From outside: a level and ruler against a gable-end rake board works the same way. Enter any rise/run pair here; it doesn’t have to be per-12.
What is the pitch multiplier for?
It converts flat footprint area into true roof surface: multiplier = √(1 + (pitch/12)²). A 2,000 sq ft footprint at 8/12 is 2,000 × 1.202 ≈ 2,404 sq ft of actual roof — what you buy shingles for.
What roof pitch is walkable?
Up to about 7/12, experienced people walk carefully on dry shingles; 8/12 and steeper needs roof jacks, staging, or a harness — and roofers price that steepness in. Never walk a wet, mossy, or metal roof at any pitch.
What is roof pitch in degrees?
Degrees = arctan(rise ÷ run). Common conversions: 4/12 = 18.4°, 6/12 = 26.6°, 8/12 = 33.7°, 12/12 = 45°. The full table on this page covers 1/12 through 12/12.