Construction

Spiral Staircase Calculator

Find steps, riser height and tread angle for a spiral stair.

Total height

Total rotation (degrees)

Target riser

Calculated Output

Number of steps 1

Riser height 1

Angle per step (°) 360

Formula: steps = ⌈height ÷ target riser⌉

Step-by-Step Breakdown

1. Values used:

2. Total height = 1

3. Total rotation = 360 degrees

4. Target riser = 1

6. Number of steps = 1

7. Riser height = 1

8. Angle per step = Total height x Total rotation = 1 x 360 = 360°

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The math behind it

steps = total height ÷ target riser (rounded up); riser = height ÷ steps; angle per step = total rotation ÷ steps.

108 in, 360°, 8 in target → 14 steps, 7.7 in risers, ~25.7°/step.

Comfortable rotation?

Around 25–30° per step is typical for a full 360° spiral.