Last updated: March 2, 2026 by Dr. David Park

How to Calculate Stair Dimensions

Formula

Proper stair design ensures safety and code compliance. Building codes typically require risers between 7 and 7.75 inches and treads at least 10 inches deep.

The stringer is the angled support board that carries the steps. Its length is calculated using the Pythagorean theorem from the total rise and total run.

Common use cases:

  • Deck stair construction
  • Interior staircase building
  • Building code verification

Frequently Asked Questions

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Dr. David Park

Applied Mathematician, PhD Mathematics

David holds a PhD in Applied Mathematics from MIT. He has published research on numerical methods and computational algorithms used in engineering and scientific calculators.

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