Roof Pitch Calculator: Find Slope, Angle & Ratio (Metric/Imperial)

What is Roof Pitch?

Roof pitch represents the slope or steepness of a roof, typically expressed as a ratio of vertical rise to horizontal run. For example, a 4/12 pitch means the roof rises 4 inches for every 12 inches of horizontal distance. Understanding roof pitch is essential for:

• Proper water drainage
• Snow load management
• Roofing material selection
• Structural integrity
• Installation requirements

Safety Notice: Before attempting any roof measurements:

• Whenever possible, measure pitch from inside the attic for safety
• If exterior measurements are necessary, use proper safety equipment including:
  • OSHA-approved fall protection
  • Non-slip footwear
  • Safety harness when required
• Consider hiring a professional for accurate measurements
• Never measure during wet, windy, or unsafe weather conditions

For outdoor electrical projects, ensure safe wire sizing with our Voltage Drop Calculator.

Step-by-Step Guide: Calculate Roof Pitch from Rise & Run

Roof pitch can be calculated using simple geometry. Here's how:

Step 1: Measure the Run

• Rise: The rise is the vertical distance from the top of the wall to the roof peak. Picture climbing a ladder to the highest point of the roof and measuring straight down to the wall base. Let’s say the rise is 1.5 meters.
• Run: The run is the horizontal distance from the wall of your building to the roof ridge. Imagine you’re standing next to your house with a tape measure stretched across the ground—it’s that distance. Let’s assume your run is 6 meters.

Step 2: Calculate the Rafter Length

Substitute your values:

Find the square root:

So, the rafter length is about 6.18 meters.

Step 3: Determine the Roof Pitch

Roof pitch is the ratio of the rise to the run. Simply divide:

Substituting:

Multiply by 100 to express it as a percentage:

Your roof pitch is 25%.

Step 4: Convert to an Angle

Use the arctangent function to convert the pitch to an angle:

Substitute:

The angle of your roof is approximately 14°.

Step 5: Express Pitch as x:12

Roof pitch is often expressed in the form of “x:12.” To find this, multiply the pitch by 12:

Substitute:

Your roof pitch is 3:12.

Summary of Results

• Rafter Length: 6.18 m

• Pitch (Percentage): 25%

• Angle: 14°

• Pitch (x:12): 3:12

Calculator Limitations: Please note that this calculator provides theoretical calculations. Actual measurements may vary due to:

• Roof irregularities and settling
• Construction variations
• Material thickness differences
• Installation methods
• Structural modifications over time Always verify calculations with physical measurements when possible.

Next, calculate your roof’s surface area with our Roof Area Calculator to estimate shingles or solar panels.

Using the Roof Pitch Calculator

Our roof pitch calculator simplifies complex calculations. Follow these steps:

1. Enter the rise (in inches, feet, centimeters, or meters)
2. Enter the run (in inches, feet, centimeters, or meters)
3. View the results for the rafter length, pitch in percentage, and angle in degrees.

Step-by-Step Example

Scenario:

• Rise = 2 meters
• Run = 5 meters

Steps:

1. Calculate the rafter length:
   
2. Find the pitch percentage:
   
3. Convert to angle:
   
4. Express as a ratio:
   

Roof Pitch Categories and Uses

Low Pitch (2/12 to 4/12)

• Perfect for modern and commercial buildings
• Suitable for regions with minimal rainfall
• Easier maintenance access
• Common in warm climates
• Requires special installation methods for asphalt shingles
• May need additional waterproofing measures

Standard/Medium Pitch (4/12 to 9/12)

• Most common for residential homes
• Excellent water drainage
• Good balance of aesthetics and functionality
• Standard installation methods apply
• Suitable for most roofing materials
• Cost-effective installation
• Ideal for most climates

Steep Pitch (9/12 and above)

• Traditional and Victorian style homes
• Superior snow shedding
• Maximum attic space
• Dramatic architectural appearance
• Higher installation costs
• Requires specialized safety equipment
• Enhanced ventilation potential

Converting Roof Pitch to Angles

For a comprehensive guide on converting between roof pitch ratios and angles, including detailed conversion charts and common applications, check out our Roof Pitch Angle Chart Calculator. It provides quick reference tables and detailed explanations for various roof pitch configurations.

Common conversions:

• 3/12 pitch = 14.0 degrees
• 4/12 pitch = 18.4 degrees
• 6/12 pitch = 26.6 degrees
• 8/12 pitch = 33.7 degrees
• 12/12 pitch = 45.0 degrees

FAQs About Roof Pitch Calculator

Remember to always consult local building codes and professional contractors when planning your roofing project. Our roof pitch calculator provides accurate calculations, but final construction decisions should consider all local requirements and professional recommendations.