Stair Calculator
Calculate stair rise and run from floor height and number of steps. Checks ergonomic comfort.
180 mm
Rise per step
| Rise | 180 mm |
| Run | 280 mm |
| Comfort 2×R+run | 640 mm |
The stair calculator works out the rise and run of each step from the total floor height and the number of steps. It also checks whether the stairs are ergonomically comfortable to climb and descend.
How the calculator works and what it’s for▾
How stairs are sized
The calculator divides the total floor height by the number of steps to find the rise of a single step in millimetres. The run, or tread depth, is entered separately, and both values are key to a comfortable stair.
Finally the calculator computes the comfort formula 2 × rise + run, which helps you judge the stair's stepping rhythm.
What you enter and what you get
You enter the total floor height, the distance between finished floor levels, in millimetres, the number of steps and the desired run.
The result shows the rise per step, the run and the comfort formula value, which let you fine-tune the number of steps.
When stairs feel comfortable
The comfort formula 2 × rise + run should land around 600–640 millimetres, so the stepping rhythm matches a natural stride. In home stairs the rise is typically about 160–190 millimetres.
A stair that is too steep is tiring and unsafe, while one that is too shallow takes up needless space.
Design tips
Adjust the number of steps until both the rise and the comfort formula fall within the recommended ranges. A small change in step count can improve the outcome considerably.
Remember that building regulations set their own minimum and maximum values, so check local requirements before you build.
🔄 Reviewed June 2026
Frequently asked questions
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