Roof pitch and rafter calculator

Convert roof pitch between rise/run, degrees and percent, and calculate common-rafter centerline and overhang geometry.

Lengths accept decimals, fractions such as 1 1/2, and explicit units such as 12 in or 5' 6 1/2". Use a dot for decimals.

Pitch rise

Pitch run

Dimension units

Ridge-to-wall horizontal run

Enter the horizontal run, not the full building width.

Horizontal overhang

Use a full span for a symmetric gable

Ridge-to-wall common-rafter centerline

13.4164ft

Nearest 1/16": 161 in. Rounding difference 0.0789 mm.

Vertical rise

6 ft

Roof angle

26.565051°

Overhang slope length

1.118 ft

Including overhang

14.5344 ft

Roof surface factor

1.118034

Equivalent pitch

6:12 · 50%

Complementary geometry: 63.434949°. Check your saw's scale convention separately.

Pitch describes a right triangle

A 6:12 pitch rises six units for every twelve units of horizontal run. It is a 50% slope, about 26.565° above horizontal. The common-rafter centerline is the run multiplied by √(1 + slope²).

These results use ideal ridge and wall intersection datums. Ridge thickness, birdsmouth, support details and physical cutting adjustments depend on how the framing is measured. The area factor applies to a simple roof plane above its horizontal projected area.

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