Roof Pitch Calculator
Calculate roof pitch, slope, and angle instantly with conversions
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Quick Answer
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, creating a 26.57° angle.
Understanding your roof pitch is essential for choosing appropriate roofing materials, calculating roof area, and ensuring proper water drainage. This calculator converts between pitch ratio, degrees, and percentage, helping you work with contractors and meet building code requirements.
Dr. Snezana Lawrence
Mathematical Historian
15+ years experience
PhD from Yale University. Published mathematical historian ensuring precision in all calculations.
Education
PhD in Mathematical History - Yale University
Understanding Roof Pitch
Key Terms
- Rise: Vertical height
- Run: Horizontal distance (usually 12")
- Angle: Degrees from horizontal
- Percentage: (rise ÷ run) × 100
Example
6" rise over 12" run = 6/12 pitch = 26.57° = 50% slope
Roof Pitch Conversion Chart
| Pitch | Angle | Percentage | Multiplier |
|---|---|---|---|
| Flat (1/12) | 4.76° | 8.3% | 1.00 |
| 2/12 | 9.46° | 16.7% | 1.01 |
| 3/12 | 14.04° | 25% | 1.03 |
| 4/12 | 18.43° | 33.3% | 1.05 |
| 5/12 | 22.62° | 41.7% | 1.08 |
| 6/12 | 26.57° | 50% | 1.12 |
| 7/12 | 30.26° | 58.3% | 1.16 |
| 8/12 | 33.69° | 66.7% | 1.20 |
| 9/12 | 36.87° | 75% | 1.25 |
| 10/12 | 39.81° | 83.3% | 1.30 |
| 12/12 | 45° | 100% | 1.41 |
Minimum Pitch by Roofing Material
| Material | Min Pitch | Notes |
|---|---|---|
| Built-up Roof | Flat (1/12) | Low-slope only |
| Modified Bitumen | 1/12 | Requires proper slope |
| TPO/EPDM | 1/12 | Flat roof membrane |
| Metal Panels | 3/12 | Standing seam |
| Asphalt Shingles | 4/12 | Most common |
| Wood Shingles | 5/12 | Higher for longevity |
| Clay/Concrete Tile | 4/12 | Check manufacturer |
| Slate | 6/12 | Premium material |
How to Measure Roof Pitch
Method 1: From Attic
- 1. Mark 12" on level from wall
- 2. Hold level horizontally
- 3. Measure vertical distance to rafter
- 4. That measurement = pitch (X/12)
Method 2: From Roof
- 1. Place level on roof
- 2. Measure 12" horizontally
- 3. Measure vertical rise at 12" mark
- 4. Rise measurement = pitch
Method 3: From Ground
- 1. Measure building width
- 2. Measure ridge height above eave
- 3. Calculate: (Height × 2) ÷ Width × 12
Frequently Asked Questions
What is a 6/12 roof pitch in degrees?
6/12 pitch = 26.57 degrees. Calculate: arctan(6÷12) × 180/π = 26.57°
What is the most common roof pitch?
4/12 to 6/12 pitch is most common for residential homes. Provides good drainage, walkable slope, and cost-effective.
What roof pitch is 45 degrees?
45 degrees = 12/12 pitch (rise equals run). This is a very steep roof, rarely used residentially.
Can you walk on a 6/12 pitch roof?
Yes, 6/12 (26.57°) is walkable with proper safety equipment. Above 7/12 becomes difficult; above 9/12 requires scaffolding.
What is the minimum pitch for asphalt shingles?
4/12 pitch minimum for asphalt shingles per most building codes. 2/12 to 4/12 requires special underlayment.
How do I calculate roof area from pitch?
Multiply base area by pitch multiplier. Example: 1000 sq ft base × 1.12 (6/12 pitch) = 1120 sq ft actual roof area.
What's the difference between pitch and slope?
Pitch = rise over run (6/12). Slope = angle in degrees (26.57°) or percentage (50%). They describe the same thing differently.
Does roof pitch affect cost?
Yes. Steeper roofs cost more due to: more materials needed, harder to work on (labor), safety equipment required, waste factor.
Dr. Snezana Lawrence
Mathematical Historian | PhD from Yale
Dr. Lawrence is a published mathematical historian with a PhD from Yale University. She ensures mathematical precision and accuracy in all our calculations, conversions, and academic score calculators. Her expertise spans computational mathematics and educational assessment.
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