Roof Pitch Calculator — Find Pitch, Angle & Multiplier

    Enter your roof's rise and run and get the pitch as X/12, the angle in degrees, and the pitch multiplier you need to accurately calculate roof surface area. No signup, no email wall.

    Vertical height

    Horizontal distance (typically 12)

    Pitch
    6/12
    Angle
    26.57°
    Multiplier
    1.1180

    What Is Roof Pitch?

    Roof pitch is the steepness of a roof, expressed as the ratio of vertical rise to horizontal run over a 12-inch span. A "6/12 pitch" means the roof rises 6 inches for every 12 inches of horizontal distance. It's the shorthand every roofer, framer, and inspector speaks in the field.

    Pitch matters for three big reasons: it changes the actual surface area of the roof (which drives material cost), it affects which materials are code-compliant (asphalt shingles generally need a minimum of 2/12), and it affects labor rates because steeper roofs are slower and more dangerous to work.

    How to Measure Roof Pitch

    The classic method is a 12-inch level and a tape measure. Hold the level horizontally with one end against the roof, then measure straight down from the 12-inch mark to the roof surface. That measurement is your rise; 12 is your run. So if it's 6 inches down, you've got a 6/12 pitch.

    You can also do it inside the attic against a rafter — safer, and you avoid climbing up top just to eyeball the slope. Newer smartphone apps and satellite tools (like RoofMammoth.ai) can pull pitch automatically without climbing anything, but the manual method is still the gold standard for verification.

    Why the Pitch Multiplier Matters

    A house's footprint in square feet is not the same as its roof surface in square feet. Pitch stretches that footprint. Multiply the footprint area by the pitch multiplier to get actual roof area. A 2,000 sq ft footprint with a 6/12 pitch is really 2,236 sq ft of roof surface (2,000 × 1.118). Skip this step and you'll under-order material every single time.

    Common Roof Pitch Reference Table

    Pitch Angle Multiplier
    1/12 4.76° 1.003
    2/12 9.46° 1.014
    3/12 14.04° 1.031
    4/12 18.43° 1.054
    5/12 22.62° 1.083
    6/12 26.57° 1.118
    7/12 30.26° 1.158
    8/12 33.69° 1.202
    9/12 36.87° 1.25
    10/12 39.81° 1.302
    11/12 42.51° 1.357
    12/12 45° 1.414

    Want instant pitch measurements from satellite? RoofMammoth.ai measures pitch, square footage, and multi-roof sections automatically the moment a homeowner enters their address.

    See how RoofMammoth measures pitch automatically