Stair Calculator
How to calculate stairs
- Enter the floor-to-floor height, measured from finished floor to finished floor.
- Enter the rise you are aiming for and the going (the depth of each tread).
- The number of steps and the exact rise appear, with the total length, the stringer and the angle.
Frequently asked questions
How is the number of steps worked out?
The height is divided by your target rise and rounded to a whole number, then the height is divided by that to give the exact rise. Every step must be the same height.
Why is the number of treads one less than the steps?
The top step is the upper floor itself, so a flight of 16 risers has 15 treads.
What is 2 × rise + going?
A rule of thumb for comfortable stairs, usually between 550 and 700 mm (about 22 to 27 inches). Building rules in your area also set maximum rise and minimum going, so check them before building.
Are my numbers sent anywhere?
No. Everything is worked out in your browser and nothing is stored or uploaded.
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