Stair Calculator

Steps, riser height, total run and stringer length from your floor-to-floor rise.

Coming soon to Google Play In review at Google Play; the link appears here when it is live.

Stair Calculator lays out a staircase from your floor-to-floor rise and a comfortable target riser height. It gives the number of steps, the exact riser height, the number of treads, the total run and the length of the stringer to cut.

Screenshots

Features

Works in centimetres or inches. No internet, no account, no data collected. For carpenters, builders and DIYers laying out stairs that are safe and even.

Number of steps (risers) and the exact riser height
Number of treads and the total run (horizontal length)
Stringer length (the sloped board to cut)

How it works

The number of risers is the total rise divided by your target riser height, rounded to the nearest whole step; the exact riser height is then the total rise divided by that number. There is one tread fewer than risers, the total run is the treads times the tread depth, and the stringer is the hypotenuse of the total rise and the total run.

Honest limits

Building codes set limits on riser height and tread depth; check your local code before you build.

Questions

How do I calculate the number of stairs?

Divide the floor-to-floor rise by your target riser height and round to the nearest whole number; that is the number of risers. Stair Calculator then gives the exact riser height.

How many treads does a staircase have?

One fewer than the number of risers, because the top riser lands on the floor above.

How long is a stair stringer?

It is the hypotenuse of the total rise and the total run: the square root of rise squared plus run squared.

Is Stair Calculator free?

Yes. It is free with ads and works offline.

Private and offline

Runs entirely on your phone and works offline. No account, no sign-up, and your data stays on your device. The app shows ads through Google AdMob; see the privacy policy. Privacy policy.

Free, with ads.