Roof Pitch Calculator
Calculate roof pitch, roof angle, slope percentage, rise, run, and rafter length from your measurements.
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Roof Pitch Results
Roof pitch is expressed as the amount of rise for every 12 inches of horizontal run.
How to Use the Roof Pitch Calculator
Our free roof pitch calculator helps you calculate roof pitch, roof angle, slope percentage, rise, run, and rafter length from your measurements. Enter the rise and run of your roof, select the appropriate units, and calculate the results instantly.
- Enter the roof rise.
- Enter the horizontal roof run.
- Select the unit for each measurement.
- Click Calculate Roof Pitch.
- Review the calculated pitch, angle, slope, and rafter length.
What Is Roof Pitch?
Roof pitch describes how much a roof rises vertically compared with its horizontal run. In residential construction, roof pitch is commonly expressed as a ratio such as 6:12.
A 6:12 roof pitch means that the roof rises 6 inches for every 12 inches of horizontal run. A higher pitch represents a steeper roof, while a lower pitch represents a shallower roof.
Roof Pitch Formula
Roof pitch can be calculated by comparing the vertical rise with the horizontal run.
Roof Pitch = Rise ÷ Run × 12
For example, if a roof rises 6 feet over a horizontal run of 12 feet, the ratio is 6:12. This can also be expressed as a 50% roof slope.
What Does This Roof Pitch Calculator Calculate?
This calculator provides several related roof measurements from the rise and run you enter.
- Roof Pitch: The rise of the roof expressed over a standard 12-inch run.
- Roof Angle: The angle of the roof measured from the horizontal.
- Roof Slope: The roof slope expressed as a percentage.
- Decimal Slope: The rise-to-run relationship expressed as a decimal.
- Rise: The vertical measurement entered for the roof.
- Run: The horizontal measurement entered for the roof.
- Rafter Length: The diagonal distance calculated from the rise and run.
Roof Pitch Example
Suppose the roof has a rise of 6 feet and a horizontal run of 12 feet. The rise-to-run relationship is 6:12.
The resulting roof pitch is 6:12, the roof slope is 50%, and the roof angle is approximately 26.57 degrees.
The rafter length for these measurements is approximately 13 feet 5 inches.
Roof Pitch vs. Roof Slope
Roof pitch and roof slope describe the same basic rise-and-run relationship, but they are commonly expressed in different ways.
Roof pitch is usually written as a ratio such as 6:12, while roof slope is often expressed as a percentage. A 6:12 roof pitch corresponds to a 50% slope.
Common Roof Pitch Values
Roofs can have many different pitches depending on the building design, climate, roofing material, drainage requirements, and construction requirements.
- 2:12 — relatively low roof pitch
- 3:12 — low roof pitch
- 4:12 — moderate roof pitch
- 5:12 — moderate roof pitch
- 6:12 — commonly used residential pitch
- 8:12 — steeper roof pitch
- 10:12 — steep roof pitch
- 12:12 — 45-degree roof pitch
How Roof Pitch Affects Rafter Length
Roof pitch affects the length of a rafter because changing the pitch changes the vertical rise for a given horizontal run.
If the horizontal run remains the same, a steeper roof produces a greater rise and therefore a longer rafter. A shallower roof produces a smaller rise and a shorter rafter.
If you need to calculate detailed rafter dimensions, you can also use our Rafter Calculator.
Roof Pitch Measurements and Units
This calculator allows you to enter rise and run measurements using different units, including feet, inches, meters, and centimeters.
Using accurate measurements is important because incorrect rise or run values will produce incorrect calculated results. Make sure your measurements represent the same section of the roof.
Frequently Asked Questions
How do you calculate roof pitch?
Roof pitch is calculated by comparing the vertical rise with the horizontal run. The result is commonly converted to a ratio based on 12 inches of run.
What does a 6:12 roof pitch mean?
A 6:12 roof pitch means the roof rises 6 inches vertically for every 12 inches of horizontal run.
What is the difference between roof pitch and roof slope?
Roof pitch is commonly expressed as a rise-over-12 ratio, such as 6:12. Roof slope is commonly expressed as a percentage. A 6:12 pitch equals a 50% slope.
Does roof pitch affect rafter length?
Yes. For the same horizontal run, increasing the roof pitch increases the vertical rise and therefore increases the rafter length.
Can I calculate roof angle from roof pitch?
Yes. Roof pitch and roof angle are mathematically related. This calculator provides the roof angle based on the rise and run you enter.
Important Information
The results provided by this calculator are mathematical estimates based on the measurements entered by the user. Actual roof construction can involve additional factors such as framing methods, structural loads, lumber dimensions, roofing materials, local building codes, and design requirements.
Always verify measurements and construction requirements before using calculator results for actual building work. Consult applicable building codes and a qualified professional when structural decisions are involved.
Related Calculators
Explore our other roofing calculators to calculate rafter dimensions, roof slope, and roof angle.
Calculate Your Roof Pitch
Enter your roof rise and run above to calculate roof pitch, slope, angle, and rafter length quickly and accurately.