8-Step Stair Stringer: Dimensions, Length & Cut Angle
Eight steps is typical for high decks and exterior landings approaching five feet. Every row is computed by the same engine as our interactive calculator.
8-step stringer dimensions · 10.5" tread
| Total Rise | Rise per Step | Total Run | Stringer Length | Cut Angle |
|---|---|---|---|---|
| 55" (4' 7") | 6.88" (6 7/8") | 73.5" | 91.8" (91 13/16") | 33.2° |
| 56" (4' 8") | 7.00" (7") | 73.5" | 92.4" (92 3/8") | 33.7° |
| 57" (4' 9") | 7.13" (7 1/8") | 73.5" | 93.0" (93") | 34.2° |
| 58" (4' 10") | 7.25" (7 1/4") | 73.5" | 93.6" (93 5/8") | 34.6° |
| 59" (4' 11") | 7.38" (7 3/8") | 73.5" | 94.3" (94 1/4") | 35.1° |
| 60" (5') | 7.50" (7 1/2") | 73.5" | 94.9" (94 7/8") | 35.5° |
| 61" (5' 1") | 7.63" (7 5/8") | 73.5" | 95.5" (95 1/2") | 36.0° |
| 62" (5' 2") | 7.75" (7 3/4") | 73.5" | 96.2" (96 3/16") | 36.4° |
Total run is fixed at 73.5" for 8 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 = 7 × 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 8 steps?
Eight steps is typical for high decks and exterior landings approaching five feet.
A 8-step stringer covers total rises from 55" (4' 7") to 62" (5' 2") while keeping every riser at or under the IRC maximum of 7¾" (R311.7.5.1). Below 55", use a 7-step stringer; above 62", move to 9 steps.
What board do you need?
The longest stringer in the table is 96.2", 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 8-step stair
- Handrail required. 8 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 8-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 8 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.