Stair Calculator: Rise, Run and Stringer
Plan a straight staircase from the total floor-to-floor rise. The calculator picks an even number of steps near your ideal riser and sizes the run and stringer.
How to calculate stairs
- Measure the total rise from finished floor to finished floor in inches.
- Set your ideal riser height and the tread run you plan to use.
- Read off the step count, riser height, total run and stringer length.
Examples
60 in rise with 7 in target riser
Total rise 60 in, ideal riser 7 in, tread run 10 in
9 steps, 6.67 in risers, 80 in run, 100 in stringer
Frequently asked questions
How many steps do I need?
Divide the total rise by your ideal riser height and round to the nearest whole number. A 60 inch rise with a 7 inch target gives 8.57, which rounds up to 9 steps.
What is a comfortable riser height?
Risers between 7 and 7.75 inches are comfortable and meet most residential codes. This tool aims for your chosen target, then splits the rise evenly so every step matches.
Why is the total run one tread shorter than the steps?
The top of the stairs lands on the upper floor, so the last riser has no tread of its own. The run therefore spans one fewer tread than the number of steps.
How is the stringer length found?
The stringer is the diagonal board the steps sit on. Its length is the hypotenuse of the total rise and total run, found with the Pythagorean theorem.
Does this meet building code?
It produces even, code-friendly proportions, but codes vary by location. Always confirm riser, tread, headroom and handrail rules with your local building department.
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