Stair Calculator

Units

Total Rise (floor-to-floor)

Vertical height from finished floor to finished floor in selected units.

Tread Depth (run per step)

Horizontal run per step (nosing-to-nosing projection) in selected units.

Riser/Steps Mode

Target Riser Step Count

Desired Riser Height

The calculator rounds to a whole number of risers; outputs actual riser.

Risers / Treads

14 risers · 13 treads

Actual Riser Height

7.71 in (= total rise ÷ risers)

Total Run (nose-to-nose)

136.5 in

Stair Angle

38.35°

Stringer Length (pitch line)

174.06 in

2R + T (rule-of-thumb)

25.93 in

Stair Calculator – Quick Cheat Sheet

Total Rise = finished-floor to finished-floor vertical distance.
Risers = either chosen directly (Step Count) or rounded from Total Rise ÷ Desired Riser.
Actual Riser = Total Rise ÷ Risers.
Treads (straight flight) = Risers − 1.
Total Run = Treads × Tread Depth (nosing-to-nosing projection).
Stringer Length ≈ √(Total Rise² + Total Run²) along the pitch line.
Angle = arctan(Total Rise ÷ Total Run).
2R + T = 2 × (Actual Riser) + (Tread Depth); a common comfort check (verify locally).

Notes & edge cases

Calculator assumes a straight flight with uniform risers/treads.
Tread nose overhangs, finish thicknesses, landings, headroom, and stringer plumb cuts are not modeled—account for these in layout.
Units are fully switchable; values convert using 25.4 mm = 1 inch.
Always check your local building code for limits and requirements.