Staircase Calculator
Design code-compliant stairs with this free calculator. Enter your total rise (floor-to-floor height) and desired tread run to get the number of risers, riser height, stringer length, and a building code compliance check based on IRC residential standards.
Enter Your Stair Dimensions
Full Breakdown
Total Rise
Number of Risers
Riser Height
Number of Treads
Tread Depth (Run)
Total Run (Horizontal)
Stringer Length
Stair Angle
Comfort Rule (2R+T)
Code Compliance
How to Use This Calculator
- Measure the total rise — the vertical distance from finished floor to finished floor, in inches.
- Enter your desired tread run (depth). 10–11 inches is standard and code-compliant.
- Click "Calculate Staircase" to see the number of risers, exact riser height, total run, and stringer length.
- Check the code compliance result to ensure your stairs meet IRC residential building codes.
The Formula
Number of Risers = Total Rise ÷ Ideal Riser Height (7.5″)
Actual Riser Height = Total Rise ÷ Number of Risers
Number of Treads = Risers − 1
Total Run = Treads × Tread Depth
Stringer Length = √(Total Rise² + Total Run²)
IRC Building Code Requirements:
- Maximum riser height: 7¾ inches (7.75″)
- Minimum riser height: 7 inches
- Minimum tread depth: 10 inches
- Comfort rule: 2×Riser + Tread should equal 24–25 inches