Roof Pitch Calculator (Rise over Run)

Measure vertical rise over horizontal run in the same units. This returns the X:12 pitch, the roof angle, and the multiplier that converts a plan footprint into roof surface area.

Quick presets (rise for a 12 in run):

Results

Pitch (X:12)—

Decimal slope (rise ÷ run)—

Roof angle—

Pitch multiplier—

Percent grade—

Formulas used

ratio      = rise / run
pitch_X    = ratio × 12          →  shown as X:12
angle°     = arctan(ratio) × (180/π)
multiplier = √(1 + ratio²)       →  roof area ≈ footprint × multiplier
% grade    = ratio × 100

Worked example: rise 6, run 12 → 6:12 pitch, 26.57°, multiplier 1.118. Carry that multiplier into the roofing squares calculator.

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