CalcArcade.

Roof Pitch Calculator

Enter the rise and run of your roof to get the pitch ratio roofers use, the angle in degrees and the factor for converting flat area to actual roof surface.

Your numbers

Result

How we calculate it

Pitch is rise per 12 inches of horizontal run: pitch = rise ÷ run × 12, so a 6-inch rise over a 12-inch run is a 6:12 roof. The angle is the arctangent of rise ÷ run.

The roof area multiplier is √(1 + (rise ÷ run)²). Multiply the footprint area by this factor to estimate the actual sloped surface area for shingles.

Assumptions and limits

  • Measure rise and run on a level line. A level and tape are enough for a quick check.
  • Pitch under about 2:12 is considered low-slope and needs special roofing materials. Many shingles require at least 4:12 for standard installation.

Frequently asked questions

What is a 6/12 roof pitch in degrees?

A 6:12 pitch is about 26.57 degrees, with a slope of 50 percent.

What is a standard roof pitch?

Many homes fall between 4:12 and 9:12. Lower pitches are common in warm, dry climates and steeper pitches in snowy areas.

How do I find roof area from pitch?

Multiply the horizontal footprint by the area multiplier shown above, then add 10 to 15 percent for waste and complex cuts.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Rise (inches) = 6; Run (inches) = 12.

  • Roof pitch 6:12
  • Roof angle 26.57 degrees
  • Slope percent 50%
  • Roof area multiplier 1.118

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.