🪜 Stair Calculator
Comfortable stairs follow one rule: risers near 7 inches, treads near 11 inches. Give the total rise (floor to floor) and this calculator splits it into an even number of risers and lays out the run.
Check your local building code before building — maximum riser height and minimum tread depth vary by jurisdiction.
How to use this calculator
Enter the total vertical rise from one floor to the next and get the riser count, riser height, tread count and total run.
- Measure the total rise in inches from the lower floor to the upper floor.
- Enter the Total rise value.
- Read the number of risers and the height of each.
- Read the tread count and the total horizontal run.
Frequently asked questions
How does the Stair Calculator split the rise?
It divides the total rise by 7 inches and rounds to the nearest whole riser, then divides the rise evenly so every step is identical. Treads use the standard 11 inch depth.
Can you give a worked example?
A 42 inch rise gives 6 risers at exactly 7 inches each, 5 treads, and a total run of 55 inches, which is 4.58 feet.
Why 7 inch risers and 11 inch treads?
That combination matches common building codes and the comfort rule that two risers plus one tread should total about 25 inches.
Can I just build to these numbers?
Use them for planning, but verify against your local building code before cutting stringers, since maximum riser height and minimum tread depth vary by jurisdiction.