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Stair Calculator
Enter total rise to get the number of steps, riser height, run and stringer length.
Number of steps
—
Risers needed.
| Riser height | — |
|---|---|
| Total run | — |
| Stringer length | — |
| Angle | — |
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Enter your figures above to see the step-by-step working.
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How the Stair Calculator Works
A comfortable, code-friendly staircase divides its total height into equal risers of about 7 to 7¾ inches. Divide the total rise by a target riser height and round to a whole number of steps, then split the rise evenly so every step is identical — uneven steps are a trip hazard and usually fail inspection. The tread depth (typically 10–11 inches) sets how far the staircase runs out horizontally.
This calculator finds the number of steps, the exact riser height, the total run, the stringer (diagonal) length for cutting, and the stair angle. Always check your local building code for exact riser and tread limits.
steps = round(total rise ÷ target riser)
Frequently Asked Questions
How many steps do I need?
Divide the total rise by a comfortable riser height (about 7.5 in) and round. A 108-inch rise needs about 14 steps.
What is a comfortable riser height?
Around 7 to 7¾ inches, with a tread depth of 10 to 11 inches. Codes set maximums, so check locally.
What is the stringer length?
The diagonal length of the board the steps attach to — the hypotenuse of the rise and run. The calculator gives it for cutting.
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