How roof slope is calculated
The tangent of the roof angle gives the relationship between rise and run. Multiplying that ratio by 12 converts it to common roofing pitch notation.
Pitch rise = tan(Roof angle) × 12
Roof slope example
An angle of approximately 26.57 degrees corresponds to a 6:12 roof pitch and a 50% slope.
What is slope percentage?
A 50% roof slope means the roof rises 0.5 units for every 1 unit of horizontal run.
Frequently asked questions
What roof pitch is 45 degrees?
A 45-degree roof has a 12:12 pitch and a 100% slope.
What roof pitch is about 26.6 degrees?
Approximately 6:12.
What is roof slope factor?
It is the multiplier used to convert horizontal footprint area to sloped roof surface area.