Stair Calculator
Estimate stair riser count, actual riser height, tread count, total run, and stair angle.
Enter your numbers
How this calculator works
Risers = total rise ÷ target riser, rounded up. Actual riser = total rise ÷ riser count. Treads are generally one fewer than risers for a typical floor-to-floor stair.
Worked example
A 108 in rise with a 7.5 in target produces 15 risers at 7.2 in each, 14 treads, and a 140 in run.
Sources & assumptions
This is a geometry layout estimate, not a code-compliance determination. Verify riser consistency, tread depth, nosing, headroom, landings, guards, and handrails with the locally adopted building code.
Frequently asked questions
Why is the number of treads one less?
For a typical stair between floors, the upper floor acts as the final walking surface. Layouts with landings or other conditions can differ.
Does this confirm code compliance?
No. Verify maximum riser, minimum tread, headroom, handrail, landing, and consistency requirements with the governing code and inspector.
Stair layout guide
Follow the complete geometry example and code-check list in the Stair rise, run, and riser count guide.