Roof Pitch Calculator
Convert rise-over-run into angle, slope factor, rafter span and simple gable roof area.
What would you like to do next?
Turn a roof pitch into slope geometry
Enter rise for twelve inches of horizontal run, building span and length, horizontal overhang and material waste. The calculator finds the angle and slope factor, applies that factor to half-span for an approximate rafter slope length and estimates the two planes of a symmetrical simple gable. The adjusted surface area provides a transparent early material reference.
Use a roof-specific plan for real work
Hips, valleys, dormers, unequal pitches, ridge details, fascia, penetrations and roof openings change area and cutting. Structural loads, member sizing, underlayment, flashing, ventilation, fall protection, manufacturer instructions and local code are outside this calculation and require qualified review.
Frequently asked questions
What does 6:12 mean?
The roof rises six inches for every twelve inches of horizontal run.
Are both roof planes included?
Yes, for the symmetrical simple gable assumed by the calculator.
Does the result size structural rafters?
No. It reports geometry and approximate area only.