What is my roof pitch? Calculate roof pitch from rise and run, convert between degrees, ratio, and percentage. Get the pitch multiplier for area estimates.
Pitch Details
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Enter your measurements to find roof pitch
Last updated March 2026 by our expert review team
| Pitch | Degrees | % Slope | Multiplier | Type |
|---|---|---|---|---|
| 1/12 | 4.8° | 8.3% | 1.003 | Flat |
| 2/12 | 9.5° | 16.7% | 1.014 | Flat |
| 3/12 | 14.0° | 25.0% | 1.031 | Low |
| 4/12 | 18.4° | 33.3% | 1.054 | Low |
| 5/12 | 22.6° | 41.7% | 1.083 | Moderate |
| 6/12 | 26.6° | 50.0% | 1.118 | Moderate |
| 8/12 | 33.7° | 66.7% | 1.202 | Moderate |
| 10/12 | 39.8° | 83.3% | 1.302 | Steep |
| 12/12 | 45.0° | 100% | 1.414 | Steep |
Multiplier converts footprint area to actual roof surface area.
Ehsan Ghazanfari
Licensed Structural Engineer
FISE-certified structural engineer with 11+ years designing bridges, retaining walls, and foundations. MSc from Aalto University.
See full profileHawkin
Certified Cost & Estimating Professional
AACE-certified estimator working with 20+ insulation companies including the two largest franchises in America.
See full profileUpdated March 2026
How we verify our calculatorsUse a 2-foot level and tape measure to find pitch: hold the level horizontally from the roof surface, measure the vertical rise at the 12-inch mark on the level.
The pitch multiplier converts flat area to actual roof area. Multiply your footprint square footage by the multiplier to get true roof surface area.
Use our roofing calculator with your pitch to estimate shingles, bundles, and material costs.
Our rafter calculator uses pitch to determine exact rafter length and birdsmouth cuts.
Pitches below 3/12 need special roofing (torch-down, TPO, or EPDM membrane). Standard shingles will not shed water properly below 2/12.
Steep pitches (10/12 and above) require roof jacks and harnesses for safety. Budget 20% more labor for pitches above 8/12.
Enter your rise and run measurements, a known angle, or a pitch ratio (X/12).
The calculator normalizes your input to a standard X/12 pitch and converts to degrees and percentage.
Get the pitch multiplier for area calculations and rafter length per 12 inches of run.
Formulas
Pitch = (Rise / Run) x 12
Angle = atan(Rise / Run) x 180 / pi
Multiplier = sqrt(1 + (Rise/Run)^2)
Rafter per 12" = sqrt(144 + Pitch^2)
How do I measure roof pitch?
Hold a level horizontally from the roof edge. Measure the vertical rise at exactly 12 inches from the start point. The rise in inches over 12 is your pitch (e.g., 6 inches of rise = 6/12 pitch).
What is a 4/12 roof pitch in degrees?
18.4 degrees. This is a low-slope roof that is easy to walk on.
What is the most common roof pitch?
4/12 to 6/12 for most residential homes. 6/12 is the most popular because it balances drainage, walkability, and aesthetics.
What roof pitch do I need for shingles?
Minimum 2/12 with special underlayment. Standard shingle installation requires 4/12 or steeper. Below 2/12, use membrane roofing.
How do I convert pitch to degrees?
Use arctangent: degrees = atan(rise/12) x 180/pi. Or use the calculator above for instant conversion.
What is a pitch multiplier?
A factor that converts flat (footprint) area to actual roof surface area. A 6/12 pitch has a multiplier of 1.118, meaning the roof is 11.8% larger than the footprint.
Can I walk on a steep roof?
Pitches up to 8/12 are walkable with caution. 9 to 12/12 requires roof jacks. Above 12/12 requires scaffolding or rope access.
Does roof pitch affect cost?
Yes. Steeper pitches require more roofing material (higher multiplier) and cost 10 to 25% more in labor due to safety equipment and slower work.
A gentle slope common on ranch-style homes. Easy to walk on and standard shingles work well.
The most popular residential pitch. Good drainage, walkable with caution, and looks proportional on most homes.
Requires roof jacks for safety. The roof surface is 30.2% larger than the footprint, so budget extra materials.
A 45-degree roof. Needs scaffolding and harnesses. The roof area is 41.4% larger than the footprint.
Measuring from the ground
Ground-level measurements are inaccurate due to perspective distortion. Always measure directly on the roof surface or from inside the attic on a rafter.
Using the wrong run value
Standard pitch notation always uses 12 inches as the run. If you measure a 24-inch run, divide the rise by 2 to normalize to X/12.
Confusing pitch with angle
A 6/12 pitch is 26.6 degrees, not 6 degrees. When talking to contractors, clarify whether you mean pitch ratio or angle in degrees.
Ignoring pitch when ordering materials
A 12/12 roof needs 41.4% more material than the same footprint with a flat roof. Always multiply footprint area by the pitch multiplier.
Using standard shingles below 2/12
Water moves slowly on low slopes and backs up under shingle tabs. Below 2/12, use membrane roofing (TPO, EPDM, or torch-down).
Important Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.