Roof Pitch Calculator
Convert roof slope (Rise/Run) to exact degrees, area multipliers, and rafter cut lengths.
Roof Slope Inputs
Understanding Roof Pitch
In construction, roof pitch is expressed as the number of vertical inches a roof rises for every 12 inches it extends horizontally. For example, a 6:12 pitch rises 6 inches vertically for every 12 inches of horizontal run.
Frequently Asked Questions
What is a 6/12 roof pitch in degrees?
A 6/12 (or 6:12) roof pitch equals an angle of 26.57 degrees. Its slope area multiplier is 1.118, meaning a roof surface is 11.8% larger than its ground footprint.
What is the most common residential roof pitch?
The most common roof pitches in North America range from 4:12 (18.43°) to 9:12 (36.87°). Pitches below 3:12 are considered low-slope and require special double-underlayment or rolled roofing membrane.
How do you calculate true roof area from pitch?
Measure the flat horizontal ground footprint of the house (e.g., 2,000 sq ft) and multiply it by the roof pitch multiplier (for a 6/12 pitch, multiplier is 1.118). 2,000 sq ft × 1.118 = 2,236 sq ft of actual roof surface area.