Premium Converters
Stair Layout
15 risers · 7.20 in riser · 35.0° angle
Generated
7/8/2026
Side view (drawn to scale)
# of risers
15
# of treads
14
Actual riser
7.20 in
Tread depth
11 in
Total run
154.00 in
Angle
35.0°
Stringer length
188.10 in
2R + T (rule)
25.40 in
IRC code check
Riser height 7.20 in ≤ 7.75 in (max)
Tread depth 11 in ≥ 10 in (min)
Comfort rule: 2R + T = 25.40 in outside 24-25 in
Step-by-step calculation
Formula
# risers = round(total rise / preferred riser). Actual riser = total rise / # risers. # treads = # risers − 1. Total run = # treads × tread depth. Stringer = √(rise² + run²).
- 1Total rise: 108 in (floor to floor).
- 2# risers = round(108 / 7) = 15.
- 3Actual riser height = 108 / 15 = 7.200 in.
- 4# treads = 15 − 1 = 14 (the top step is the floor).
- 5Total run = 14 × 11 = 154.00 in.
- 6Stringer length = √(108² + 154.00²) = 188.10 in.
- 7Stair angle = arctan(108 / 154.00) = 35.04°.
- 8Code: max riser 7.75 in, min tread 10 in. Comfort rule: 2R + T should be 24-25 in.