Plan a straight staircase from the total rise between floors. The calculator finds the fewest equal steps that keep each riser under your maximum height, then works out the run, the stringer length and the stair angle.
Building codes set limits on riser height, tread depth, headroom and handrails. The defaults follow the US International Residential Code; always check the rules where you live.
Formula
Risers = ⌈Total rise ÷ Max riser⌉ · Riser height = Total rise ÷ Risers
There is one fewer tread than risers, because the top floor acts as the last step. Total run = Treads × Tread depth, and the stringer length is √(Rise² + Run²).
Worked example
A 108-inch (9 ft) floor-to-floor rise with a 7¾-inch maximum riser needs ⌈108 ÷ 7.75⌉ = 14 risers of 7.71 in. With 13 treads of 10 in, the total run is 130 in (10 ft 10 in) and the stringer is about 169 in (14 ft 1 in) long.
Frequently asked questions
What is the standard stair rise and run?
US residential code allows risers up to 7¾ in and treads of at least 10 in. A rise of about 7 in with an 11 in tread is often considered most comfortable.
How do I measure total rise?
Measure vertically from the finished floor at the bottom to the finished floor at the top, allowing for any flooring still to be laid.
Last updated · Calculations checked by automated tests· Editorial policy