Stair Rise, Run & Stringer
Number of risers, riser height, tread depth, total run, stringer length, and angle for a straight flight — checked only against the limits you enter.
A stair layout from the floor-to-floor height: how many steps, how tall and deep each is, how far the flight runs, and how long to cut the stringers.
Example: A 108 in floor-to-floor rise at a 7 in target: 15 risers of 7.2 in, 14 treads of 10 in, a 140 in run and a 176.8 in stringer.
Divide the rise,
then measure the run.
How the step count is chosen, what the stringer length means, and whose rules apply.
Risers and treads
The total rise (finished floor to finished floor) is divided into equal risers: the count is the rise ÷ your target riser height, rounded to the nearest whole number, and you can override it. The actual riser is rise ÷ count. A flight whose top step is the upper floor has one tread fewer than risers; deck stairs with a cut top tread have as many treads as risers. Total run = treads × tread depth; the going (the walking surface) adds any nosing.
Stringer, angle, and 2R + T
The stringer length is the hypotenuse of rise and run (√(rise² + run²)) — the line from the bottom of the first riser to the top of the last, before any allowance for the stringer's own depth, thickness, or attachment. The angle is atan(rise ÷ run). 2R + T (twice the riser plus the tread) is a long-used comfort rule of thumb; it is shown as a number, not judged.
Limits are yours
Maximum riser, minimum tread, headroom, handrails, landings, and riser-variation rules come from the building code that applies to your job. This page embeds none of them: enter your limits and it tells you whether the layout meets those; it never states code compliance. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.