Stair Calculator
Lay out a straight stair from total rise, a maximum riser height and selected tread depth before checking local code constraints.
Stair dimensions are code-sensitive. Verify minimum tread, maximum riser, headroom, landings, handrails and permitted nosing with the code adopted in your jurisdiction.
How this tool works
Riser count = ceiling(total rise ÷ maximum riser). Actual riser = total rise ÷ riser count. A typical straight flight has one fewer tread than risers.
Example
A 108-inch floor-to-floor rise with a 7.5-inch maximum creates enough equal risers to stay at or below the selected limit.
Common questions
Can I use this as a permit design?
No. Stair geometry is safety- and code-sensitive; verify adopted building-code requirements and field dimensions.
Why are there fewer treads than risers?
For a simple stair terminating at an upper floor, the upper floor surface acts as the final landing rather than another separate tread.