Calculate stair dimensions: number of risers, riser height, tread depth, and total run based on floor height.
| Dimension | Minimum | Maximum |
|---|---|---|
| Riser height | 4" | 7¾" |
| Tread depth | 10" | — |
| Stair width | 36" | — |
| Headroom | 6\'8" | — |
| Handrail height | 34" | 38" |
The 7-11 rule is a quick guideline: 7" riser + 11" tread feels most comfortable. The sum of riser + tread should be 17-18 inches.
A standard 9-foot ceiling (108 inches total height with floor framing) needs about 14-15 risers at 7.25-7.5 inches each.
30-35° is ideal for residential stairs. Below 20° feels like a ramp; above 40° feels steep.
Try this related calculator.
Open →Try this related calculator.
Open →Try this related calculator.
Open →Enter the total rise (floor-to-floor height) and available run length. The calculator determines the number of steps, riser height, tread depth, and stringer length.
Risers = Total Rise / Ideal Rise (7-8 inches). Treads = Risers – 1. Stringer Length = √(Total Rise² + Total Run²). Code: Riser 7-7.75", Tread 10-11", Riser + Tread = 17-18".
Total rise 9 ft (108"): Risers = 108/7.5 = 14.4 → 15 risers at 7.2" each. 14 treads at 10" = 140" run (11.67 ft). Stringer ≈ 14.6 ft.
All risers must be the same height (code requirement, and safety). The 7/11 rule: 7" riser + 11" tread is the most comfortable. Check local building codes — handrails are required for 4+ risers.