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Stairs Calc

Stair How-To Guides

Practical, step-by-step guides for building and finishing stairs — each one paired with the free Stairs Calc calculator that does the math for you.

Step-by-step stair guides

Each guide walks one job end to end — measuring, laying out, and building — and links straight to the free Stairs Calc calculator that does the math, so you can read the method and get your exact numbers in the same place.

How to Cut Stair Stringers A measure-twice, cut-once walkthrough for laying out and cutting a notched stair stringer with a framing square — including the bottom-riser drop everyone forgets. How to Install a Stair Handrail Measure, lay out, and mount a code-height stair handrail — including the grip height window and the top and bottom extensions inspectors check first. How to Space Balusters Evenly The exact method for laying out balusters so the gaps are equal, the ends look intentional, and no point in the railing passes a 4-inch sphere. How to Build Deck Stairs From total deck height to a finished, code-compliant flight: how to split the rise, cut the stringers, anchor a footing, and tie it all to the deck. How to Estimate Concrete for Stairs How to turn step dimensions into cubic yards, cubic meters, and bag counts — using the waist-slab method and a builder’s 10% waste margin. How to Carpet Stairs How to measure a stair runner so you order enough carpet the first time — tread plus riser plus nosing wrap, converted to yardage with a waste margin. How to Measure for a Staircase The three measurements every stair starts from — total rise, available run, and headroom — taken accurately so the steps come out equal and legal the first time. How to Calculate Stair Stringer Length The exact math behind a stringer length — the staircase triangle and Pythagoras — plus how to choose board size, keep the throat strong, and buy a little long. How to Build Winder Stairs How to turn a staircase with winder treads instead of a landing — laying out pie-shaped steps that keep a legal run at the walkline and a safe, even climb. How to Fix Steep Stairs Why a staircase feels steep, how to measure the real problem, and the concrete ways to bring the pitch back into the comfortable, code-legal range. How to Make a Stair 3D Model Build a custom staircase to your exact rise, run, width and shape, then download it as a Wavefront .obj you can drop straight into Blender, Unity, Unreal or Godot at real-world scale — free, in the browser, no account.

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.