Roof Pitch Calculator

Calculate roof pitch, rise, run, and rafter length from angle or rise measurements. Helps with roofing material estimates.

Roof Angle (degrees)

Rise (inches)

Run (inches)

Result

Please check your inputs.

📖 How to Use This Tool

Choose your input method — either enter the rise and run measurements (in inches or feet) or the roof angle in degrees.

Type the values into the corresponding fields. For rise/run, measure the vertical height (rise) and horizontal span (run) of the roof.

Click the 'Calculate' button. The tool instantly computes the roof pitch (as a ratio), rafter length, and slope.

Review the results displayed clearly — pitch is shown as X:12 (e.g., 6:12), and the rafter length is given for your run.

Use the pitch and rafter length to estimate roofing materials such as shingles, underlayment, or rafters.

📝 What Is Roof Pitch Calculator?

Roof pitch is the steepness or slope of a roof, typically expressed as a ratio of vertical rise over horizontal run (e.g., 6:12 means the roof rises 6 inches for every 12 inches of horizontal distance). Understanding your roof pitch is crucial for choosing the right roofing materials, ensuring proper water runoff, and complying with local building codes. Our Roof Pitch Calculator simplifies this process by instantly converting between rise/run, angle, and rafter length — saving you time and reducing errors.

This tool matters because an accurate pitch measurement directly impacts material quantities (like shingles or tiles), structural design, and installation costs. Whether you're a homeowner planning a DIY project or a contractor estimating a job, knowing the exact pitch helps avoid waste and ensures a safe, durable roof. By just entering two known values, you get all critical dimensions for your project.

🧮 Formula

The tool uses the standard roof pitch formula:

Pitch (ratio) = Rise / Run To express pitch in the common X:12 format: Pitch (X:12) = (Rise / Run) × 12 Rafter Length = √(Rise² + Run²) (if rise and run are known) If using an angle: Rafter Length = Run / cos(Angle) Variables: Rise = vertical height of the roof from the top of the wall to the ridge; Run = horizontal distance from the outside wall to the ridge center; Angle = the slope angle in degrees. The calculator handles both metric and imperial units.

💡 Tips for Best Results

✨📏 Measure run from the outside of the wall to the exact center of the ridge for accuracy — don't include overhangs.

✨🧮 Always use the same unit (inches or feet) for both rise and run to avoid calculation errors.

✨🏠 For material estimates, add 10-15% extra to rafter length for overhangs, birdsmouth cuts, and waste.

✨🔢 If you know the angle, double-check with a speed square or digital level to ensure your input is correct.

❓ Frequently Asked Questions

What does a 6/12 roof pitch mean?

A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. It's a moderate slope common in many residential homes, offering good drainage and walkability.

How do I measure roof pitch without climbing onto the roof?

You can measure from inside the attic. Place a level against a rafter, measure 12 inches horizontally from the rafter bottom, then measure the vertical distance from that point to the rafter — this gives you the rise per 12 inches (the pitch).

What is the most common roof pitch for houses?

In many regions, the most common residential roof pitch is between 4/12 and 9/12. A 4/12 pitch is considered low slope, while 6/12 is a standard mid-range pitch that works well with asphalt shingles.