How to calculate stairs
Risers = ⌈rise ÷ target riser⌉ · Treads = risers − 1 · Run = treads × tread depth
Worked example. Number of risers: 15 steps.
Example inputs — Total rise (floor to floor): 108 in; Target riser height: 7.5 in; Tread depth: 10 in. Starting values are illustrative.
Within typical US residential code (≤ 7¾″ riser, ≥ 10″ tread)
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Divide the total rise by your target riser height and round up to get the number of steps, then spread the rise evenly so every step is the same height.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
What's a comfortable stair?
A common rule is riser × 2 + tread ≈ 25″. For example, 7.25″ risers with 10.5″ treads.