Roof Pitch Calculator
Calculate roof pitch ratio and slope angle from rise and run.
Roof Pitch: —
Roof Pitch FAQ
What is a 6/12 pitch?
The roof rises 6 inches for every 12 inches of horizontal run — about 26.6°.
What pitch is walkable?
Pitches up to 6/12 are generally walkable with proper footwear. Above 9/12 is steep and typically requires staging.
Results are estimates for planning purposes. Verify with product labels and local requirements before purchasing materials.
How to calculate roof pitch
Roof pitch is the ratio of vertical rise to horizontal run, expressed as X/12. A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance toward the ridge.
The formula is: Pitch = (Rise ÷ Run) × 12
To convert pitch to degrees: Angle = arctan(Rise ÷ Run)
Enter your rise and run in the calculator above — any units work as long as they match, since the ratio is what matters.
Roof pitch chart: common pitches, angles, and applications
| Pitch | Angle | Classification | Common application | Walkable? |
|---|---|---|---|---|
| 2/12 | 9.5° | Low slope | Flat-look modern, additions | With care |
| 3/12 | 14.0° | Low slope | Sheds, garage additions | With care |
| 4/12 | 18.4° | Moderate | Ranch homes, common residential | Yes |
| 5/12 | 22.6° | Moderate | Colonial, split-level homes | Yes |
| 6/12 | 26.6° | Standard | Most common US residential | Yes |
| 7/12 | 30.3° | Moderate steep | Farmhouse, craftsman styles | With caution |
| 8/12 | 33.7° | Steep | Cape Cod, colonial styles | Risky |
| 10/12 | 39.8° | Very steep | Victorians, chalet style | Staging needed |
| 12/12 | 45.0° | Very steep | Decorative gables, alpine | Staging needed |
How roof pitch affects your project
Roofing materials and minimum pitch requirements
| Material | Minimum pitch | Notes |
|---|---|---|
| Asphalt shingles | 4/12 standard (2/12 with special underlayment) | Most common material |
| Metal (standing seam) | 1/12 | Best choice for low slopes |
| Metal (exposed fastener) | 3/12 | More affordable metal option |
| Wood shakes | 4/12 | Require good ventilation |
| Slate | 4/12 | Heavy — needs structural assessment |
| Clay/concrete tile | 4/12 to 5/12 | Very heavy, needs engineer review |
| EPDM rubber (flat roof) | 0/12 to 1/12 | For very low or flat slopes only |
Impact on material quantity and labor cost
A steeper pitch means more roof surface area over the same building footprint. A 12/12 pitch has approximately 41% more surface area than a 4/12 pitch over the same base area.
Labor costs increase significantly above 8/12 because roofers require safety staging and work more slowly. Expect to pay 15–30% more in labor for pitches above 9/12 compared to standard 6/12 installations.
Frequently asked questions about roof pitch
What is a good roof pitch?
6/12 is the most common residential roof pitch in the US. It provides good water drainage, works with all standard roofing materials, and is walkable for most roofing work without staging.
How do I measure roof pitch from the ground?
Use a smartphone app with an inclinometer feature pointed at the roof slope to get the angle. Or, from inside the attic, hold a carpenter's level horizontally and measure up 12 inches on the level, then measure straight down to the rafter — that measurement is your rise.
What pitch do I need for asphalt shingles?
Asphalt shingles require a minimum pitch of 4/12 for standard installation. Between 2/12 and 4/12, shingles can be used with special double-layer underlayment. Below 2/12 requires a flat roofing system.
What is the minimum slope for a metal roof?
Standing seam metal roofing can be installed on pitches as low as 1/12 with proper sealant. Exposed-fastener metal panels require a minimum 3/12 pitch. Metal roofing handles low slopes much better than asphalt shingles.
How does roof pitch affect material cost?
Steeper roofs require more material — a 12/12 pitch has significantly more surface area than a 4/12 pitch over the same building footprint. Installation labor costs also increase substantially above 8/12 due to safety requirements and staging.
What is a 4/12 roof pitch in degrees?
A 4/12 roof pitch equals approximately 18.4 degrees. A 6/12 pitch is about 26.6 degrees. A 12/12 pitch is exactly 45 degrees.
Can I walk on a 6/12 roof?
Yes, a 6/12 pitch is generally walkable with proper rubber-soled footwear and caution. Anything above 8/12 typically requires roof brackets or staging for safe access. Never walk on a wet roof regardless of pitch.
Related tools
- Square Footage Calculator — calculate your building footprint area
- Stair Rise Calculator — calculate rise and run for stairs
- Paint Coverage Calculator — estimate exterior paint after roofing
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