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(701)814-6992
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Ratkeville, Bahamas.
Shed Roof Slope Calculator
Determine the pitch, rise, and rafter length for your single-slope shed roof project.
Shed Dimensions
Width of the shed from low wall to high wall.
Rafter Length
0' 0"
Total length including overhang
Profile Visualization
Pitch: 4/12
Roof Rise
0"
Angle
0°
Slope Factor
0
Tail Length
0"
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What is a Shed Roof Slope Calculator?
A Shed Roof Slope Calculator is a specialized tool for designing single-slope (skillion) roofs common on sheds, lean-tos, and modern homes. It helps builders determine the vertical rise needed to achieve a specific pitch over a given horizontal distance, ensuring proper water drainage and structural layout.
How to Use This Tool
3 Easy Steps
Plan your roof.
1
Measure Run
Input the total horizontal distance (width) of the shed.
2
Choose Pitch
Select your desired slope (e.g., 4/12 for standard drainage). This is essential when knowing how to calculate roof pitch.
3
See Results
Get the rafter length and the wall height difference immediately.
Calculation Methodology
The Math Behind the Slope
Understanding how to calculate roof pitch involves basic trigonometry. The roof forms a right triangle where the run is the base and the rise is the height.
Total Rise = Run × (Pitch / 12)
Rafter Length = √(Run² + Rise²)
Angle = arctan(Pitch / 12)
For practical applications, always add the overhang length to your final rafter cut list.
Measuring Existing Slopes
If you are renovating and need to know how to measure roof slope on an existing shed, you can use a level and a tape measure.
Simply mark 12 inches on the level, hold it perfectly horizontal, and measure the vertical distance from the 12-inch mark down to the roof surface. That measurement is your pitch (e.g., 4 inches means a 4/12 pitch).
Related Calculators
Frequently Asked Questions
For asphalt shingles, a 2/12 pitch is generally the minimum, requiring special underlayment. For metal roofs, you can go as low as 1/12, but proper sealing is critical to prevent leaks.
Most smartphones have a built-in level or measure app. Simply place the phone on the roof surface (or a board laying on it) to see the angle in degrees.
Typically, the "Run" refers to the horizontal distance between the supporting walls. The overhang is calculated separately and added to the rafter length afterwards.
A skillion roof is another name for a mono-pitch or single-slope roof. It is the most common design for modern sheds because it is easy to frame and drains water effectively.
User Reviews
James Dalton
Carpenter
"Used this to frame my garden shed. The wall height difference calculation was spot on."
Sarah Miller
DIYer
"Great simple tool. Wish it had a metric option though."
David Ross
Contractor
"Saves me a ton of time on small outbuilding jobs."
Mike L.
First-time User
"Fine, but could be clearer on what 'Run' means."
Emily Chen
Architect
"The visualization is simple but effective."
James Lee
Estimator
"Straightforward and precise."
Karen White
Homeowner
"Finally, I understand how to calculate roof pitch properly. This tool is a lifesaver."
Robert King
Builder
"Nice app, but I wish I could switch to metric easily."
John Davis
Fabricator
"Helped me check my homework for structural analysis class. Accurate results."
Have Feedback or a Question?
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