Stair Calculator: Rise, Run and Stringer

It divides the total rise by your ideal riser height and rounds to the nearest whole number, never below one. A 60 inch rise with a 7 inch target gives 8.57, which rounds up to 9 steps.

The ideal riser only chooses the step count. Once the count is fixed, the tool divides the total rise evenly by it, so every step is identical. A 60 inch rise over 9 steps gives 6.6667 inch risers rather than exactly 7.

Risers between about 7 and 7.75 inches are comfortable and meet most residential codes. Aiming for 7 and letting the tool split the rise evenly keeps every step within a safe, consistent range.

The top step lands on the upper floor, so the final riser has no tread of its own. The run therefore spans one fewer tread than the number of steps: 9 steps at a 10 inch run give 80 inches, not 90.

The stringer is the diagonal board the steps rest on. Its length is the hypotenuse of the total rise and total run: the square root of rise squared plus run squared. A 60 inch rise and 80 inch run give a clean 100 inch stringer.

Everything is in inches. Enter the rise, riser and tread in inches and every result comes back in inches, rounded to four decimal places. Convert feet to inches first by multiplying by 12.

No. It models an idealized rise and run and does not add board thickness, nosing overhang, or floor finish. Treat the stringer length as a cut-line reference and confirm against your actual lumber before cutting.

It produces even, code-friendly proportions, but codes vary by location. Always confirm riser height, tread depth, headroom, and handrail rules with your local building department before building.

No. The math runs entirely in your browser, so your measurements stay on your device and nothing is uploaded.