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Free for contractors
Roof pitch calculator
Pitch, angle, rafter length and shingle squares. Nothing you type is saved.
Your roof
A 6/12 roof rises 6 inches for every 12 inches across.
Width is the span across the gable, eave to eave on the walls. Simple two-sided gable roof.
Results
6/12
Roof pitch
Angle
Slope
Rafter length (with overhang)
Roof area
Squares (100 sq ft each)
Squares with waste
Bundles at 3 per square
How the numbers work
Pitch is rise over a 12-inch run. The angle is the arctangent of rise divided by 12, and the slope factor is the square root of 1 plus (rise ÷ 12) squared. Rafter length is the horizontal run (half the width plus the overhang) times that slope factor. Roof area is both sides of the roof at that length, across the building length plus overhang on each end.
This is a planning estimate for a simple gable roof. It leaves out hips, valleys, dormers, chimneys, starter and ridge cap. Measure the roof before you order material.
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