Roof pitch calculator
Enter the rise and run, or the angle, and get the pitch in every form a roofer or a supplier will ask for.
Pitch
0
How it works
Pitch is how many inches the roof rises for every 12 inches it runs horizontally. A 6/12 roof climbs 6 inches per foot.
pitch = rise / run x 12 angle = atan(rise / run) slope factor = sqrt(rise^2 + run^2) / run roof area = footprint area x slope factor
The slope factor is the number that matters for ordering. Multiply the flat footprint of a plane by it to get the area you actually cover with shingles. Rafter length is the horizontal run times the same factor, before the overhang.
Common roof pitches
| Pitch | Angle | Slope factor | Typical use |
|---|---|---|---|
| 2/12 | 9.5 degrees | 1.014 | Low slope: needs special underlayment for shingles |
| 3/12 | 14.0 degrees | 1.031 | Porches, sheds, low ranch roofs |
| 4/12 | 18.4 degrees | 1.054 | The minimum for standard shingle installs |
| 5/12 | 22.6 degrees | 1.083 | Ranch houses and additions |
| 6/12 | 26.6 degrees | 1.118 | The most common US house pitch |
| 7/12 | 30.3 degrees | 1.158 | Suburban two-storey homes |
| 8/12 | 33.7 degrees | 1.202 | Steeper suburban roofs |
| 9/12 | 36.9 degrees | 1.250 | Colonials and Cape Cods |
| 10/12 | 39.8 degrees | 1.302 | Steep: harness and toe boards |
| 12/12 | 45.0 degrees | 1.414 | 45 degrees: A-frames and Tudors |
How to find the pitch without climbing
From the ground, the usual trick is a level and a tape against the rake board or a gable. Hold the level horizontal with one end on the roof edge, mark 12 inches along it and measure straight up to the roof. That number is the pitch.
A LiDAR measurement does the same job for every plane at once. The aircraft records the height of the roof surface every few inches, and fitting a plane to those points gives its pitch and direction. On the roofs we checked against EagleView and Roofr reports, the main pitch came out within 1/12 every time.
More roof calculators
Skip the tape measure
Type an address and RoofTools measures the roof from public LiDAR: every plane's pitch, direction and sloped area, the total in squares, and sun and shade for a solar layout. Then you can fix any plane in the editor.
Want someone to do the job?
Tell us where and when, and we'll put you in touch with a roofer or solar installer near you. No account needed.