Stair Calculator
Explore equal risers from a measured floor-to-floor rise and a chosen maximum target height. The results separate the flight run from the top landing and show the theoretical diagonal stringer length. A simple sketch makes the step count easier to review.
Your result
How the calculation works
Riser count = ceil(total rise / target maximum riser). Equal riser = total rise / count. Tread count = riser count − 1. Run = tread count × going. Stringer = √(rise²+run²).
Worked example
A 2.8 m rise with a 0.18 m maximum target gives 16 risers, each 0.175 m high. Fifteen 0.28 m treads give a 4.2 m flight run and a 5.048 m theoretical diagonal.
Assumptions and limitations
The top floor serves as the last tread. This is a straight-flight geometry model with at most 500 risers. Targets are user assumptions, not building-code limits; sketch is schematic.
Confirm local stair rules, headroom, nosings, landings, guards, handrails and structural requirements. The diagonal is not a fabrication-ready cut length.
Sources and editorial responsibility
Maintained by Renvoro Pty Ltd. Sources inform the methods and assumptions shown here; outputs have the limitations described on this page.
Method reviewed 2026-10-13. Calculation standards · Report an issue