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Stairs Calc

L-shaped stairs

A staircase with a 90° turn, made with a quarter landing or winders.

L-shaped (quarter-turn) stairs change direction once by 90°, using either a flat landing or a set of winders at the corner. They fit into a corner of a room, give a natural resting point, and feel less imposing than a long straight flight. A U-shaped (half-turn) stair simply adds a second 90° turn. Example: a 16-riser flight split 8-and-8 around a quarter landing keeps each leg short while the total rise stays the same. The turn does not change riser height; it only rearranges the total run into two directions. Codes apply the normal riser, run, headroom, and handrail rules to each leg independently.

Try the calculator L‑Shaped & U‑Shaped Staircase Calculator

Related terms

Winder A wedge-shaped tread that turns a staircase without a flat landing. Landing A flat platform that breaks a flight or changes its direction. Walkline The path 12 in in from the inside of a turn, where winder tread depth is measured. Spiral staircase A helical stair whose wedge treads wind around a central column.

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L‑Shaped & U‑Shaped Staircase Calculator Design quarter‑turn (L), half‑turn (U) and winder stairs — Stairs Calc sizes each flight, lays out the turn, and checks winder treads at the walkline.
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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.