Stairs for a 108 in (9 ft) rise
A rise of 108 in (9 ft) is typical for a standard 9 ft floor-to-floor staircase. Measure the total rise from the lower finished surface to the finished upper floor or deck surface, including the thickness of the tread boards. The count below is for 10 in treads and a 7¼ in target riser.
| Item | Value |
|---|---|
| Number of risers | 15 |
| Riser height | 7.200 in |
| Number of treads | 14 |
| Total run | 11.67 ft (140.0 in) |
| Stringer length | 14.73 ft |
| Board to buy | 16 ft |
| Angle | 37.6° |
Effect of tread depth
Deeper treads make a gentler stair but need more room. Typical US code asks for at least 10 in.
| Tread depth | Treads | Run (in) | Run (ft) | Stringer | Angle |
|---|---|---|---|---|---|
| 9 in | 14 | 126 in | 10.5 ft | 13.8 ft | 40.6° |
| 10 in | 14 | 140 in | 11.7 ft | 14.7 ft | 37.6° |
| 11 in | 14 | 154 in | 12.8 ft | 15.7 ft | 35.0° |
| 12 in | 14 | 168 in | 14.0 ft | 16.6 ft | 32.7° |
Effect of riser height
Taller risers mean fewer steps but a steeper stair. Typical US code caps risers at 7¾ in.
| Target riser | Risers | Actual riser | Treads | Run (ft) |
|---|---|---|---|---|
| 7 in | 15 | 7.20 in | 14 | 11.7 ft |
| 7.25 in | 15 | 7.20 in | 14 | 11.7 ft |
| 7.5 in | 14 | 7.71 in | 13 | 10.8 ft |
| 7.75 in | 14 | 7.71 in | 13 | 10.8 ft |
Use the stair calculator to enter your own rise and tread depth. Stairs are a safety item: US codes usually require a handrail from four risers up, and a guard at drops over 30 in, so confirm the rules with your building department. Planning a deck? See the deck materials calculator.
Want to change anything else? The calculator above is the full Stair Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How many steps for a 108 in (9 ft) rise?
15 risers (steps up), each 7.20 in tall, with 14 treads, because the upper floor is the top step. This uses a 7¼ in target riser. A 7 in target gives 15 risers.
How long is the run for a 108 in (9 ft) rise?
11.67 ft (140 in) with 10 in treads. The stringer is 14.73 ft long, so buy a 16 ft board.
What is the angle of stairs for a 108 in (9 ft) rise?
37.6 degrees with 10 in treads. Typical stairs run between about 30 and 40 degrees. Deeper treads make the stair shallower.
Related sizes and guides
Related sizes
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.