Roof Pitch Calculator
Calculate roof pitch from rise and run, convert between degrees and ratios
Calculate pitch from measurements
Quick presets
inches
inches
Roof Pitch
6/12
26.6° • 50.0% slope • 1.118 multiplier
PRO
Professional Calculator
Calculate total area for complex roofs with multiple sections
ft
ft
Total Roof Area
1,389 sq ft
Sections
2
Total Squares
13.9
Cost Breakdown
Section 1: $1,054 (76%)
Section 2: $335 (24%)
Detailed Breakdown
Section 11,054 sq ft
Dimensions40 × 25 ft (footprint: 1,000 sq ft)
Pitch4/12 (×1.054)
Section 2335 sq ft
Dimensions20 × 15 ft (footprint: 300 sq ft)
Pitch6/12 (×1.118)
Total Roof Area1,389 sq ft
Total Squares13.9
Bundles (10% waste)46
How to Use This Calculator
Rise & Run: Enter the rise (vertical) and run (horizontal) measurements in inches. The standard convention is to express run as 12 inches (e.g., "6/12" means 6 inches of rise per 12 inches of run).
From Angle: If you know the roof angle in degrees, enter it to get the equivalent pitch ratio and area multiplier.
From Ratio: Select a known pitch from the dropdown to see its degrees, multiplier, rafter factor, and description.
The Formula
Pitch Ratio = Rise / Run (typically expressed as X/12)
Angle (degrees) = arctan(Rise / Run) × (180 / π)
Slope (%) = (Rise / Run) × 100
Area Multiplier = √(1 + (Rise/Run)²)
Rafter Length = Run × Area Multiplier
Example Calculation
Measuring from her attic, Lisa places a level against a rafter and measures:
• 12 inches horizontally along the level
• 6 inches vertically down to the rafter
• 12 inches horizontally along the level
• 6 inches vertically down to the rafter
Her pitch is 6/12, which equals:
• 26.6 degrees
• 50% slope
• 1.118 area multiplier (her roof area is 11.8% larger than the footprint)
• For every 12 ft of horizontal run, her rafters are 13.4 ft long
Frequently Asked Questions
How do I measure roof pitch from inside my attic?
Place a level horizontally against a rafter. Measure 12 inches along the level from where it touches the rafter. Then measure the vertical distance from that 12-inch mark straight down to the rafter. That vertical measurement is your rise. If you measure 6 inches, your pitch is 6/12.
What is the most common roof pitch?
The most common roof pitch for residential homes in the US is between 4/12 and 6/12. A 4/12 pitch (18.4°) is the minimum recommended for standard asphalt shingles. A 6/12 pitch (26.6°) provides a good balance of aesthetics and drainage.
What roof pitch is considered steep?
A roof pitch of 8/12 (33.7°) or higher is generally considered steep. Steep roofs may require additional safety equipment for installation and can cost more for labor. Pitches above 12/12 (45°) are extreme and rare in residential construction.