4/12 Pitch Roof Calculator [ Rafter Length, Slope, Angle ]
To calculate the actual roof length, divide the horizontal span (S) by the cosine of the pitch angle (θ).
The 4/12 Pitch Roof Calculator helps homeowners and builders easily determine the slope, rise, and overall dimensions of a roof with a 4:12 pitch. This means for every 12 horizontal inches, the roof rises 4 inches vertically.
Formula:
| Variable | Meaning |
|---|---|
| R | Roof length (actual run of the pitched roof) |
| S | Horizontal span of the roof |
| θ | Roof pitch angle (in degrees) |
Solved Calculation:
Example 1:
Given Values:
- S = 20 feet
- θ = 18.43° (which corresponds to a 4/12 pitch)
| Calculation | Instructions |
|---|---|
| R = | Divide the horizontal span by the cosine of the pitch angle. |
| R ≈ | Calculate the cosine of 18.43°. |
| R ≈ 21.06 feet | Perform the division to get the roof length. |
Answer: R ≈ 21.06 feet
Example 2:
Given Values:
- S = 30 feet
- θ = 18.43° (which corresponds to a 4/12 pitch)
| Calculation | Instructions |
|---|---|
| R = | Divide the horizontal span by the cosine of the pitch angle. |
| R ≈ | Calculate the cosine of 18.43°. |
| R ≈ 31.60 feet | Perform the division to get the roof length. |
Answer: R ≈ 31.60 feet
What is 4/12 Pitch Roof Calculator ? Calculate Rafter Length, Roof Sheathing, Pitch, Slope, Angle – 2025
A 4/12 pitch roof means that the roof rises 4 inches for every 12 inches of horizontal run. This pitch translates to an angle of about 18.43 degrees, which is common for residential buildings.
To calculate the size of a 4/12 pitch roof, you can use the formula: (rise ÷ run) = pitch. For example, if you need to determine the roof height, the 4/12 Pitch Roof Calculator will help you input the necessary values such as roof length and width, to find the overall roof area and height. This is especially useful for estimating material costs, such as shingles or insulation.
The calculator can also convert the pitch into different units like degrees or percentage for ease of understanding. For instance, the 4/12 roof pitch corresponds to a slope of 33.3%.
Final Words:
Moreover, the calculator offers the flexibility to estimate the total square footage, which is essential for determining how many square feet of roofing materials you’ll need. It even provides a multiplier based on the pitch to help calculate the roofing surface accurately. Whether you’re working on a new roof installation or a repair project, this tool ensures you get the correct measurements and materials for the job.
