How to plan an L-shaped staircase.
An L-shaped (also called quarter-turn) staircase changes direction by 90° at a landing or a set of winder treads. It saves footprint, breaks long runs into safer segments, and is the most common house-stair geometry in Europe.
What makes an L-shape different from straight stairs?
A straight flight needs roughly 2.5–3 m of clear horizontal run for a typical floor-to-floor of 2.8 m. An L-shape splits that run across two walls, giving you back square meters of useful floor space. The trade-off is the corner: either a landing (a flat platform) or two-to-four winder treads that taper around the inner string. The calculator above lets you toggle between these in Winder Settings → Turn Type.
Five rules to get right before you cut wood
- Rise per step ≈ 170–185 mm. Comfortable for daily use. Anything above 200 mm becomes tiring; below 140 mm wastes vertical space.
- Tread depth ≥ 230 mm. Your foot needs landing space. With a 30 mm overhang you can cheat the going down to 250 mm, but never less.
- 2 × rise + tread = 580–650 mm. The classic stride formula. Stay inside this band and the stair will feel right under any leg length.
- Walk-line at 200–250 mm from the inner string. The walk-line is the imaginary path a person takes through the winder. DIN 18065 requires at least 100 mm of tread at this point — the calculator flags this live.
- Headroom ≥ 2.0 m. Measured perpendicular from any tread nosing up to the ceiling or upper-floor opening edge.
Winder corner vs. landing — which to choose?
Winder treads keep the stair compact and visually flowing, but the inner string feels narrow underfoot — not ideal for elderly users or anyone carrying laundry. A landing breaks the climb in two and gives you a safe pause point, but it adds around 800 mm to the long side of the footprint. Below 2.7 m of available floor length, winders are usually the only way to fit the stair at all.
How to read the live preview
The 3D view is purely illustrative — useful for sharing with a client or spouse. The 2D Top view is what your carpenter needs to verify the stair fits the room. The X-Ray view shows the stringer / dado joinery without removing surrounding parts. All three update from the same geometry model the moment you change a slider on the left.
What you'll get when you export
Every export speaks back to the live geometry above — the moment you tweak a parameter, the next download reflects the change. Five formats are available:
- PDF · multi-sheet A3 construction drawing. A3 landscape, ready to print. Sheets cover the project summary, plan view, both run elevations, scaled workshop drawings for stringers / treads / risers / newels / handrail / balusters with dado and mortise pockets, and a bill of materials. Drawings are scaled to fit A3 (typically 1:10 or 1:20 depending on the part) — use this PDF as the on-site reference and quote document, not as a cutting template.
- DXF · 1:1 CAD/CNC zip. One file per category (plan, both elevations, each part family) at true 1:1 scale in the chosen unit — every contour is the actual cut path. Named layers separate stringers, treads, risers, newels, handrail, balusters, dado and mortise cutouts. Loads straight into AutoCAD, BricsCAD, LibreCAD, and any CNC post-processor as workshop-ready templates.
- SVG · 1:1 vector zip. Same nine drawings as the DXF, also at true 1:1 scale, but as plain SVG — open in any browser, Illustrator, Inkscape, or Affinity Designer. Useful for clients who don't have CAD installed, or for laser cutters that prefer SVG input.
- STL · 3D printable mesh. A single solid model for slicing and 3D printing the design as a tabletop reference, or for importing into visualization tools (Blender, Twinmotion, Lumion).
- STEP · parametric CAD exchange. Each part — every stringer, tread, riser, newel, handrail piece, baluster — as a separate body with its mortise and dado pockets baked in as proper B-Rep solids. Opens natively in SolidWorks, Inventor, Fusion 360, FreeCAD, and SolidEdge for further design work or assembly checks.
What the files do not include
The downloads are a construction foundation, not a turnkey product. Depending on your specific configuration, joinery details (tenon shoulders, post mortises, baluster sockets), tread/riser overlap at the apex, and stringer-to-newel connections may need minor on-site adjustments by your carpenter. The geometry pipeline is conservative — when in doubt it errs on the side of clear space — so the parts will fit, but the final aesthetic millwork (chamfers, fillets, plug covers, sanding profiles) is up to whoever builds it. Always verify all dimensions on site before cutting wood.
Two scope notes specific to this calculator:
- Mortise-and-tenon joinery is only generated with closed stringers. Open (saw-tooth) and no-stringer configurations rely on surface-mounted treads and skip the tenon / dado pockets — the part outlines stay correct, but post-to-stringer connections must be detailed by your carpenter.
- Handrail and balusters are orientation-only. They define positions, lengths, angles, and cross-section sizes so the parts list and plan reflect reality — but the drawings do not include the joinery itself (newel-post mortises for the handrail, baluster drill sockets, dowel pins, anchor screws). Use them as a layout reference and detail the connections during install.