About this calculator
Convert any way of stating roof pitch into the others. Canadian roofers say "6 in 12" (6/12), though plans often give the slope as a ratio such as 1 in 2. This also gives the pitch factor for converting plan area to roof area.
How it’s calculated
Slope t = rise ÷ run. Degrees = atan(t). x/12 = t × 12. Percent = t × 100. Pitch factor = √(1 + t²). Hip/valley factor (per unit of common run) = √(2 + t²).
Worked example
With these inputs:
- I know
- Pitch as x/12
- Rise per 12
- 6
the result is:
- Pitch
- 6/12 = 26.57°
- Degrees
- 26.57°
- Pitch (x in 12)
- 6 in 12
- Percent grade
- 50%
- Ratio
- 1 : 2
Tips from the trade
- To measure pitch, hold a level horizontally against the roof and measure 12" (or 1 m) along it. The vertical gap down to the roof is the rise.
- From inside the attic, measure the rafter angle with a digital angle finder.
Common questions
What is a 4/12 pitch in degrees?
18.43°.
What is 35° as x/12?
About 8.4/12.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the building code adopted in your province before ordering.