Shed Roof Pitch Calculator
Framing a shed? Enter the shed’s width and the heights of the high and low walls — this shed roof pitch calculator returns the pitch (X/12), the angle in degrees, the rafter length, and the roof area you need to cover.
Width is the horizontal run of the single slope. Depth is used only for the roof-area estimate.
Planning estimates only — verify against local building codes and roofing-manufacturer requirements before you build.
How the shed roof pitch calculator works
On a single-slope (mono-pitch) shed, the roof’s run is simply the shed’s width, and the rise is the difference between the high-wall and low-wall heights. This calculator turns those two numbers into the standard pitch notation (rise per 12 inches of run), the angle in degrees, and the rafter length via the Pythagorean theorem.
The rafter length is the number that matters at the lumber yard: it is the hypotenuse of the width and rise, so a 8 ft wide shed with 1 ft of rise needs rafters of about 8.06 ft before overhang. Multiply by the shed depth for the roof area, then add 10–15% waste for cuts.
rise = high − low · pitch = rise/width × 12 · angle = atan(rise/width) · rafter = √(width²+rise²)
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Shed roof pitch calculator FAQ
What is a good roof pitch for a shed?
Most sheds use 2/12 to 4/12 — low enough for a simple single-slope build, steep enough to shed water. In heavy-snow areas, go steeper (4/12+) so snow slides off instead of loading the rafters.
How do you calculate shed roof pitch?
Subtract the low wall height from the high wall height to get the rise, divide by the shed width (the run), and multiply by 12. Example: an 8 ft wide shed with walls at 8 ft and 7 ft has 1 ft of rise, so (1 ÷ 8) × 12 = 1.5/12 pitch.
What is the minimum pitch for a shingle shed roof?
Most asphalt shingles require at least 2/12, and some manufacturers insist on 3/12 or special underlayment below 4/12. Below 2/12, use standing-seam metal or a membrane roof instead.
How long should shed rafters be?
Rafter length is the hypotenuse: √(width² + rise²). Add 6–12 inches of overhang past the low wall for drip edge, and a couple of inches at the ridge for the birdsmouth cut.
Single-slope or gable roof for a shed?
Single-slope (mono-pitch) is simpler: two wall heights, one set of identical rafters, no ridge beam. A gable roof sheds snow better and gives headroom, but doubles the framing complexity.