Roof Pitch Calculator

Calculate roof pitch as a ratio (X:12), angle in degrees, slope percentage, and rafter length from rise and run measurements.

Vertical height

Horizontal distance

Pitch
:12
Angle
°
Slope
%
Rafter Length
"

Formulas

Pitch = (Rise ÷ Run) × 12
Angle = arctan(Rise ÷ Run)
Slope % = (Rise ÷ Run) × 100
Rafter = √(Rise² + Run²)

FAQ

Most residential roofs have a pitch between 4:12 and 9:12. A 6:12 pitch (about 26.6°) is very common for standard homes.
Roofs with a pitch below 2:12 are considered flat or low-slope. They require special roofing materials like EPDM or TPO since shingles cannot shed water at such low angles.

Pro Tip

Roof pitch is expressed as rise over a 12-inch run. A "6/12 pitch" means the roof rises 6 inches for every 12 inches of horizontal distance.

Common Roof Pitches

Flat roof0.5:12-2:12
Low slope2:12-4:12
Standard4:12-9:12
Steep9:12-18:12

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