About the Stair Calculator
A comfortable staircase follows a simple rule: twice the rise plus the going should come to about 630 mm. Enter the floor-to-floor height and this calculator works out how many steps you need, the exact rise of each, the going, the total run and the headroom — then checks it all against normal domestic limits.
Also known as: staircase calculator, stair rise and run, step calculator, stair dimensions, how many stairs.
How to use this calculator
- Enter total floor-to-floor height, maximum rise per step, going (tread depth), stair width and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Open “Step-by-step” to see how the answer was worked out.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
risers = ceil(height ÷ max rise) · rise = height ÷ risers
Worked example
Using the values pre-filled in the calculator above:
- Total floor-to-floor height = 2,700 mm
- Maximum rise per step = 200 mm
- Going (tread depth) = 250 mm
- Stair width = 900 mm
- Nosing overhang = 25 mm
the calculator returns:
- Number of risers: 14
- Rise of each step: 192.86 mm
- Number of treads: 13
- Total run: 3,250 mm
Working
2,700 mm ÷ 200 mm = 13.50 → 14 risers2,700 ÷ 14 = 192.86 mm actual rise