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Stairs Calc

Number of risers

How many equal steps the flight has; total rise divided by target riser, rounded.

The number of risers is how many equal steps your flight is divided into. You get it by dividing the total rise by a comfortable target riser height and rounding to a whole number, then dividing the rise back by that count so every riser is exactly equal. A flight always has one more riser than treads: a 14-riser stair has 13 treads. Example: 112 in rise ÷ 7.5 in ≈ 14.9, round to 15 risers at 7.47 in each. Rounding up gives gentler steps; rounding down gives a steeper but shorter staircase. The 3⁄8 in uniformity rule is satisfied automatically because the count is a whole number.

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Related terms

Total rise Vertical distance from the lower finished floor to the upper finished floor. Riser height The vertical height of a single step; every riser must be equal within 3⁄8 in. Tread The horizontal board you step on; its depth equals the run plus the nosing.

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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.