Stair angle (pitch)
The slope of the flight in degrees; comfortable stairs sit around 30–37°.
The stair angle, or pitch, is the slope of the whole flight measured from horizontal. It is the arctangent of riser height divided by run. Example: a 7.5 in riser over a 10 in run gives atan(7.5 ÷ 10) ≈ 36.9°. Comfortable, everyday stairs land between about 30° and 37°; steeper than 42° feels like a ladder and tires the legs, while shallower than 27° eats floor space. The IRC does not state an angle directly — it caps the riser and sets a minimum run, which together bound the pitch to roughly 37° maximum. UK Approved Document K caps private stairs at 42°. Pitch is the quickest gut-check for whether a layout will feel right.
Related terms
Stair calculators
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Written by the Stairs Calc editorial team. Methodology and code references: see our methodology.
Built and maintained by builders, drafters and engineers who plan stairs for a living — every code limit is transcribed from the published standard and cited to its exact section.
Last reviewed 2026-06-20 against IRC 2021/2024
Stairs Calc gives accurate geometry and checks it against published building-code limits, but results are estimates for planning. Codes are adopted and amended locally and change over time. Always confirm dimensions against your local adopted code and a licensed professional before you build.