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Stair Layout & Framing

Stair Calculator

Calculate the number of steps, riser height, tread run, and stringer length for a staircase, given the total floor-to-floor rise.

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Stair Dimensions

Result


Enter total rise to calculate stair layout
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Disclaimer: This calculator provides a planning estimate only and is not a substitute for a licensed contractor or structural engineer. Always verify riser height, tread depth, and headroom against your local building code before construction.

About the Stair Calculator

Designing a safe, comfortable staircase means dividing the total floor-to-floor rise into an even number of equal-height steps, each paired with a consistent tread depth for a comfortable stride.

How It Works

This calculator divides your total rise by a target riser height to find the ideal whole number of risers, then recalculates the exact riser height so all steps are perfectly even — a critical safety requirement, since uneven risers are a leading cause of stair falls.

Stringer Length

The stringer is the diagonal structural board that supports the treads. Its length is calculated using the Pythagorean theorem from the total rise and total run (horizontal distance covered by all treads combined).

Frequently Asked Questions

Most US residential building codes (IRC) cap riser height at 7.75 inches, with a minimum tread depth of 10 inches. Always verify your local code, as requirements can vary by jurisdiction and stair type.
Uneven risers are one of the most common causes of trips and falls on stairs, since people unconsciously expect a consistent step height once they start climbing. Building codes typically require riser height variance of no more than 3/8 inch between the largest and smallest step.
The stringer is the zigzag-cut structural board (or engineered stringer) that runs diagonally from the bottom to top of the staircase, supporting the treads and risers. Most staircases use 2-3 stringers depending on width and load.
There's always one fewer tread than risers, because the top riser leads directly onto the upper floor surface, which acts as the final "tread." For example, 14 risers means 13 physical treads.
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