Stair Calculator – Number of Steps, Rise & Run
Building a staircase? Our stair calculator finds the ideal number of steps, rise height, and run depth based on your total rise — so your stairs meet building code and feel comfortable to climb.
Stair Calculator
Standard Stair Dimensions (IRC Building Code)
| Measurement | IRC Code Requirement |
|---|---|
| Max Riser Height | 8.25 inches |
| Min Riser Height | 4 inches |
| Min Tread Depth | 9 inches |
| Min Width | 36 inches |
| Handrail Height | 34–38 inches |
FAQs
What is the ideal stair riser height?
The most comfortable riser height is 7 to 7.5 inches. The IRC building code allows a maximum of 8.25 inches. Lower risers (6–7 in) feel easier to climb but require more steps.
How do I calculate stair rise and run?
Divide the total floor-to-floor height by your desired riser height to get the number of steps. Then multiply steps by tread depth to get total run. Our calculator does this automatically.
What is a stringer?
The stringer is the diagonal support board that the treads sit on. Its length is calculated using the Pythagorean theorem: √(rise² + run²).