Staircase Stringer Calculator

Staircase Stringer Calculator

Building a staircase? This calculator ensures every riser comes out perfectly even, a critical safety requirement.

Number of Risers = round(Total Rise / Target Riser Height)
Actual Riser Height = Total Rise / Number of Risers

Example

108 inches total rise, targeting 7.5-inch risers:

Number of Risers = 14 → 7.71 in actual height each (13 treads)

Why the Actual Height Differs From the Target

Building codes commonly require riser heights within a narrow range, often 7-7.75 inches - since total rise rarely divides evenly by the target height, the number of risers is rounded to a whole number first, then the actual per-riser height is recalculated to distribute the total rise evenly across that whole number of risers.

Why Even Risers Are a Hard Safety Requirement

Building codes critically require every riser in a single staircase to be equal height within a very small tolerance - even a small unevenness between risers is a well-documented trip hazard, since people naturally develop a consistent stepping rhythm expecting each riser to match the previous one exactly.