Stair Calculator
Rise, run, stringer length for any staircase
📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
Free stair calculator
Calculate stair risers, run, stringer. Code-compliant rise/run ratio.
How to use this tool
- 1
Enter total rise
Floor-to-floor vertical height (inches or cm).
- 2
Enter run depth
Desired tread depth per step (typical: 10-11 in).
- 3
See step plan
Number of risers, riser height, stringer length.
Frequently Asked Questions
What is a safe rise/run ratio?
IRC code: max 7¾ in rise, min 10 in run. Rise + run should equal 17-18 in total. Consistent rise between all steps is critical.
How to calculate stringer length
Stringer = √(total rise² + total run²). The hypotenuse of the right triangle formed by the staircase.
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