Stair Calculator App — Rise, Run, Stringers, and Code Checks

Stairs are the one thing in construction where the math has to be perfect. One wrong riser height and you've got a trip hazard. One wrong run and you fail inspection. There's no "close enough" with stairs.

Stair Pro is a free, standalone stair calculator that gives you everything you need to lay out stairs correctly — and tells you whether your design meets building code before you cut the first stringer.

What Stair Pro Calculates

• Rise and run — enter total height, get individual riser height and tread depth.
• Number of treads and risers — automatic count based on your dimensions.
• Stringer layout — length, angle, and cut dimensions.
• Pitch angle — displayed in degrees.
• Total run — horizontal distance the staircase covers.
• IBC/IRC code compliance — checks your riser height, tread depth, and headroom against building code requirements and flags any violations.
• Side elevation drawing — visual representation of your stair layout so you can see it before you build it.

Why Code Checks Matter

Building inspectors measure stairs. If your risers aren't consistent or your treads are too shallow, you're tearing it out and rebuilding. Stair Pro checks your design against IBC and IRC code requirements automatically — so you know it'll pass before you pour or cut.

Completely Free

Stair Pro is 100% free. No trial, no subscription. It works offline, on your phone, and supports both metric and imperial. It's a tool every contractor should have bookmarked.