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Stairs Calc

Run (going)

The horizontal depth of one step, measured nosing-to-nosing, not counting the overhang.

The run — called the going in the UK and most of Europe — is the horizontal depth you travel forward on each step, measured from the face of one nosing to the next. It is not the same as tread depth: the tread board is the run plus the nosing overhang. Example: an 11 in (279 mm) run with a 1 in nosing means an 11 in run but a 12 in tread board. The IRC sets a minimum 10 in (254 mm) run for residential stairs; UK Approved Document K asks for at least a 220 mm going. A deeper run feels safer underfoot but lengthens the staircase.

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Related terms

Tread The horizontal board you step on; its depth equals the run plus the nosing. Nosing The lip of the tread that overhangs the riser below; ¾–1¼ in in the IRC. Total run The horizontal distance the whole flight covers, floor to floor. Walkline The path 12 in in from the inside of a turn, where winder tread depth is measured.

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Stair Rise and Run Calculator Turn one total‑rise measurement into equal risers and runs that meet code — with the comfort rules (2R+T and Rise+Run) checked for you.
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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.