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Roof Pitch Calculator

Convert roof pitch between every form — rise/run (x / 12), angle in degrees, slope percentage, and the pitch factor — plus rafter length and ridge height for your span, with a diagram and downloadable PDF.

U.S. roof pitch is written as rise over a 12-inch run (for example 6 / 12). Rafter length here excludes ridge-board thickness and birdsmouth cuts. For planning purposes only.

Pitch Input
1 Enter Your Pitch
in
/
in
Hold a level out 12 in from the roof and measure straight down to the surface for rise
°
From a phone level app or an angle finder on the rafter
%
Rise divided by run, times 100 (a 6/12 roof is 50%)
2 Rafter & Ridge (optional)
ft
Wall-to-wall width. A gable rafter spans half of this each side.
in
Added to the rafter length (leave 0 for none)
Pitch Results
Roof Pitch
—
Enter your pitch to begin
Angle —
Slope Grade —
Pitch Factor —
Pitch Conversions
Rise over run —
Pitch (x / 12)—
Ratio (simplified)—
Angle—
Slope grade—
Pitch factor (multiplier)—
Rafter Length —
Ridge Rise —
Rise per 12 in —
Roof Slope Diagram
Rise, run, rafter & angle (not to scale for steep pitches)
Common Pitch Reference
PitchAngleGradeFactor

The highlighted row is closest to your pitch. Pitch factor multiplies flat area to get sloped roof area.