Stair Calculator – Rise, Run and Number of Steps
Calculate stair rise, run, and step count for any staircase. Includes IRC code compliance for decks, basements, and interior stairs.
📏 Construction📐 Steps = Total Rise / Rise per Step
Total floor-to-floor rise (inches)
Rise per step (in)
Run per step (in)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Stair Calculator – Rise, Run and Number of Steps | Steps = Total Rise / Rise per Step | steps |
Step-by-Step Examples
Example 1
Basement 9 ft
108 inch rise, 7 in rise, 11 in run.
- Steps: 15 | Actual rise: 7.2 in | Total run: 13.75 ft
- IRC: PASS
✓ 15 steps
Example 2
Deck 36 inches
36 inch rise to deck.
- Steps: 5 | Rise: 7.2 in | Run: 4.6 ft
✓ 5 steps
Example 3
Second Floor 10 ft
120 inch rise, 7.5 in rise, 10 in run.
- Steps: 16 | Total run: 13.3 ft
✓ 16 steps
Real-World Applications
Builders
Calculate stair layout for any project.
Contractors
Verify stair design meets IRC code.
DIYers
Build deck or basement stairs.
Architects
Quick stair layout for preliminary design.
Common Mistakes to Avoid
⚠️
Wrong total rise
Measure finished floor to finished floor — not framing to framing.
⚠️
Not checking local code
IRC max rise 7.75 in, min run 10 in. Local codes may be stricter.
Frequently Asked Questions
Standard rise and run? ▾
IRC: max rise 7.75 in, min run 10 in. Comfortable: 7 in rise, 11 in run. Rise + run = 17-18 inches.
Stairs for 9-foot ceiling? ▾
108 inches. At 7 in rise: 15 steps. At 7.5 in: 14 steps.
Comfortable stair angle? ▾
30-35 degrees for most people. Above 45 degrees is too steep for regular use.
When is handrail required? ▾
IRC requires a handrail for 4 or more risers. Must be 34-38 inches above stair nosing.