Riser height: 7.38 in (18.76 cm)
Tread depth: 10.5 in (26.67 cm)
Total run: 126 in (320.04 cm)
Stringer length: 158.4 in (402.35 cm)
How to use this stair calculator
Enter the total rise, which is the vertical height from the lower floor to the upper floor. The calculator gives you the number of steps, the riser height, the tread depth, the total run, and the stringer length. Use the Inches or cm button to switch units. If you switch units, your entered number is converted so the physical height stays the same.
How stair math works
Steps are found by dividing the total rise by 7.75 inches, the common maximum riser height, and rounding up. That keeps every riser at or under 7.75 inches. The actual riser height is the total rise divided by the number of steps. Tread depth is 10.5 inches, above the common 10 inch minimum. Total run is the tread depth times the number of steps minus 1, because the top step is the upper floor itself. Stringer length is the diagonal of the total rise and total run.
Stair examples
| Total rise | Steps | Riser height | Total run | Stringer length |
|---|---|---|---|---|
| 96 in (8 ft) | 13 | 7.38 in | 126 in | 158.4 in |
| 105 in (8 ft 9 in) | 14 | 7.5 in | 136.5 in | 172.21 in |
| 120 in (10 ft) | 16 | 7.5 in | 157.5 in | 198.01 in |
Frequently asked questions
How many steps do I need for an 8 foot rise?
An 8 foot rise is 96 inches, which needs 13 steps at a 7.38 inch riser height.
What is the standard riser height?
Most stairs use a riser height near 7 to 7.5 inches. Common US residential code sets a maximum riser height of 7.75 inches. Always check your local code before building.
Do I count the top step?
No. The top step is the upper floor itself, so the total run uses one fewer tread than the number of steps.
What tread depth should I use?
This calculator uses 10.5 inches, which is above the common 10 inch minimum. Deeper treads are more comfortable but need more total run.