Spiral Staircase Calculator
Estimate step count, tread angle, and run for spiral stairs
Spiral Staircase Calculator
Table of Contents
How to Use the Spiral Staircase Calculator
Enter the total vertical height (floor to floor), your desired step rise, the width of each step, and the diameter of the central pole (all in millimeters). The calculator will estimate the number of steps, tread angle, total run, and actual step rise.
Calculation Method
The calculator uses the following formulas:
- Number of Steps = ceil(Total Height ÷ Step Rise)
- Tread Angle = 360° ÷ Step Count
- Total Run = 2 × π × (Pole Diameter ÷ 2 + Step Width ÷ 2) ÷ 1000
- Actual Step Rise = Total Height ÷ Step Count
All dimensions are in millimeters and converted to meters where needed.
Factors Affecting Staircase Design
- Step rise: Typical residential stairs use 170-200 mm per step.
- Step width: Wider steps increase the run and comfort.
- Pole diameter: Affects the inner radius and run.
- Total height: Determines the number of steps required.
Practical Applications
- Residential spiral staircases
- Loft and mezzanine access
- Outdoor deck stairs
- Space-saving stair designs
Tips for Building Spiral Stairs
- Check local building codes for minimum/maximum step rise and width.
- Ensure handrails are included for safety.
- Use sturdy materials for structural integrity.
- Plan for comfortable tread depth and headroom.
Frequently Asked Questions
How do I calculate the number of steps for a spiral staircase?
Divide the total height by the desired step rise and round up. The calculator does this automatically.
What is the tread angle per step?
It's the angle each step covers in the spiral, calculated as 360° divided by the number of steps.
How do I determine the run of the staircase?
The run is the circumference at the center of the tread, based on the step width and central pole diameter.