11-Step Stair Stringer: Dimensions, Length & Cut Angle
Eleven steps covers tall walk-outs and interior flights in homes with lower ceilings. Every row is computed by the same engine as our interactive calculator.
11-step stringer dimensions · 10.5" tread
| Total Rise | Rise per Step | Total Run | Stringer Length | Cut Angle |
|---|---|---|---|---|
| 78" (6' 6") | 7.09" (7 1/16") | 105" | 130.8" (130 13/16") | 34.0° |
| 79" (6' 7") | 7.18" (7 1/8") | 105" | 131.4" (131 3/8") | 34.4° |
| 80" (6' 8") | 7.27" (7 1/4") | 105" | 132.0" (132") | 34.7° |
| 81" (6' 9") | 7.36" (7 5/16") | 105" | 132.6" (132 5/8") | 35.0° |
| 82" (6' 10") | 7.45" (7 7/16") | 105" | 133.2" (133 1/4") | 35.4° |
| 83" (6' 11") | 7.55" (7 1/2") | 105" | 133.8" (133 13/16") | 35.7° |
| 84" (7') | 7.64" (7 5/8") | 105" | 134.5" (134 7/16") | 36.0° |
| 85" (7' 1") | 7.73" (7 11/16") | 105" | 135.1" (135 1/16") | 36.4° |
Total run is fixed at 105" for 11 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 = 10 × 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 11 steps?
Eleven steps covers tall walk-outs and interior flights in homes with lower ceilings.
A 11-step stringer covers total rises from 78" (6' 6") to 85" (7' 1") while keeping every riser at or under the IRC maximum of 7¾" (R311.7.5.1). Below 78", use a 10-step stringer; above 85", move to 12 steps.
What board do you need?
The longest stringer in the table is 135.1", so a 12-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 11-step stair
- Handrail required. 11 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 11-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 11 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.