Roof Pitch Calculator - Calculate Roof Angle, Slope & Pitch Ratio
Free calculator to determine precise roof pitch measurements including pitch ratio, slope angle, rise per foot, and percentage slope for construction projects
Roof Pitch Calculator
Results
What is a Roof Pitch Calculator?
A Roof Pitch Calculator is a free construction tool that helps you determine the exact angle, slope, and pitch ratio of your roof. It calculates roof measurements based on rise and run or span and pitch for accurate roofing projects and construction planning.
This calculator works for:
- New Roof Construction - Plan pitch for new building projects
- Roof Replacement - Match existing roof pitch for repairs
- Construction Planning - Determine structural requirements
- DIY Roofing Projects - Calculate precise measurements for home improvement
How Roof Pitch Calculation Works
The calculation uses these formulas:
Where:
- Rise = Vertical height from wall to ridge
- Run = Horizontal distance (half the span)
- Span = Total width from wall to wall
- Angle = Roof slope in degrees
Key Roof Pitch Concepts Explained
Pitch Ratio
Expressed as X:12, where X is the rise in inches per 12 inches of horizontal run.
Roof Slope
The steepness of the roof, calculated as rise divided by run, expressed as a percentage.
Roof Angle
The angle in degrees between the roof surface and horizontal, calculated using trigonometry.
Standard Pitches
Common residential pitches range from 3/12 (low slope) to 12/12 (steep slope).
How to Use This Roof Pitch Calculator
Enter Rise
Measure vertical height to ridge
Enter Run
Measure horizontal distance (half span)
Get Results
View pitch ratio, angle, and slope
Use for Planning
Apply measurements to your project
Benefits of Using This Calculator
- • Accurate Planning: Get precise roof measurements for construction projects.
- • Material Estimates: Calculate exact material requirements based on roof pitch.
- • Code Compliance: Ensure roof pitch meets local building codes and standards.
- • Drainage Planning: Determine if pitch allows proper water and snow runoff.
Factors That Affect Your Results
1. Building Type
Different building types require different pitch ranges for optimal performance and aesthetics.
2. Climate Conditions
Regions with heavy snow require steeper pitches, while mild climates can use lower slopes.
3. Roofing Materials
Some materials require minimum pitch angles for proper installation and water shedding.
Frequently Asked Questions (FAQ)
Q: How do I calculate roof pitch?
A: Roof pitch is calculated by dividing the total rise by the total run and multiplying by 12. The formula is: Pitch = (Rise ÷ Run) × 12. This gives you the rise in inches per foot of horizontal run.
Q: What is a 4/12 roof pitch?
A: A 4/12 roof pitch means the roof rises 4 inches for every 12 inches of horizontal run. This represents a moderate slope that's commonly used in residential construction and is easy to walk on safely.
Q: What is the difference between pitch and slope?
A: Pitch and slope are essentially the same thing, expressed differently. Pitch is traditionally expressed as a ratio (like 4/12), while slope is often expressed as a percentage or decimal (33.3% or 0.333).
Q: How do I measure roof pitch on an existing roof?
A: To measure roof pitch on an existing roof, place a level against the roof surface and measure the vertical rise over a 12-inch horizontal distance. The level should be perfectly level, and you'll measure the height difference at the 12-inch mark.