9-Step Stair Stringer: Dimensions, Length & Cut Angle
Nine steps appears on tall walk-out decks and short interior half-flights. Every row is computed by the same engine as our interactive calculator.
9-step stringer dimensions · 10.5" tread
| Total Rise | Rise per Step | Total Run | Stringer Length | Cut Angle |
|---|---|---|---|---|
| 63" (5' 3") | 7.00" (7") | 84" | 105.0" (105") | 33.7° |
| 64" (5' 4") | 7.11" (7 1/16") | 84" | 105.6" (105 5/8") | 34.1° |
| 65" (5' 5") | 7.22" (7 3/16") | 84" | 106.2" (106 3/16") | 34.5° |
| 66" (5' 6") | 7.33" (7 5/16") | 84" | 106.8" (106 13/16") | 34.9° |
| 67" (5' 7") | 7.44" (7 7/16") | 84" | 107.4" (107 7/16") | 35.3° |
| 68" (5' 8") | 7.56" (7 1/2") | 84" | 108.1" (108 1/16") | 35.7° |
| 69" (5' 9") | 7.67" (7 5/8") | 84" | 108.7" (108 11/16") | 36.1° |
Total run is fixed at 84" for 9 steps with a 10.5" tread: (steps − 1) × tread, because the upper floor or deck acts as the top step. For a different tread depth, total run = 8 × tread.
Rise per step is floored to the nearest 1/16" for framing-square layout. Different total rise? Use the interactive stringer calculator.
When do you need 9 steps?
Nine steps appears on tall walk-out decks and short interior half-flights.
A 9-step stringer covers total rises from 63" (5' 3") to 69" (5' 9") while keeping every riser at or under the IRC maximum of 7¾" (R311.7.5.1). Below 63", use a 8-step stringer; above 69", move to 10 steps.
What board do you need?
The longest stringer in the table is 108.7", so a 10-foot 2×12 covers every case with layout margin. Use solid, straight-grained 2×12 stock — after notching, the remaining "throat" must keep at least 3.5" of material for structural integrity.
Code checkpoints for a 9-step stair
- Handrail required. 9 risers is at or over the 4-riser threshold — a graspable handrail is required on at least one side (IRC R311.7.8).
- Guards required. Every total rise in the 9-step range exceeds 30", so open sides of the walking surface need 36" guards (IRC R312.1.1–.2) — see the baluster spacing calculator.
- Riser uniformity: the largest and smallest riser may differ by no more than 3/8" (IRC R311.7.5.1) — divide total rise by 9 and mark every notch from the same reference edge.
- Drop the bottom riser by one tread thickness so the first step matches the rest after treads go on.