How to use the Stair Calculator
The stair calculator finds the number of steps, riser height, run and stringer length for a staircase.
What you need to enter
- Total rise (in)
- Tread depth (in)
- Maximum riser height (in)
The formula
Risers = ceil(total rise ÷ maximum riser). Riser height = total rise ÷ risers. Run = tread depth × (risers − 1).
Worked example
Using the default values in the calculator:
- Total rise (in): 108
- Tread depth (in): 10
- Maximum riser height (in): 7.75
| Number of risers | 14 |
| Riser height | 7.714 in |
| Total run | 130 in |
| Stringer length | 169.01 in |
| Stair angle | 37.6° |
Tips for better results
- Check local building code for limits.
- Keep every riser equal.
Common mistakes to avoid
- Unequal risers.
- Forgetting the top step.
Please note: Results are estimates for general use. For safety-critical work such as electrical or building projects, check with a qualified professional and local codes. See our Disclaimer.