Stair Calculator
Calculate the number of steps, riser height and total run for a straight staircase.
Building codes set legal maximum riser heights, minimum tread depths, headroom and handrail rules, and they differ by country. Always check your local regulations.
About this tool
Enter the total height from floor to floor, the maximum riser height you want and the tread depth. The calculator gives the number of risers and treads, the exact riser height, the total horizontal run and checks the step against the classic comfort rule.
Frequently asked questions
Divide the total rise (floor to floor) by your maximum riser height and round up. For a 270 cm rise and 18 cm maximum riser, you need 15 risers of exactly 18 cm, and 14 treads.
Common guidance is a riser of 15–19 cm (6–7.75 in) and a tread of 25–30 cm (10–11 in). The traditional comfort rule says 2 × riser + tread should be about 60–65 cm (24–25.5 in).
The top step is the upper floor itself, so a straight stair always has one tread less than it has risers.
It gives the geometry only. Building codes set maximum riser heights, minimum treads, headroom, handrails and balusters, and they differ between countries — always check your local rules.
Related tools
Concrete CalculatorWork out how much concrete you need for a slab, patio or footing — in m³, yd³ and premix bags.Roof Pitch CalculatorConvert rise and run into roof pitch, angle in degrees, slope percentage and rafter length.Decking CalculatorWork out how many deck boards and joists you need for a rectangular deck, including gaps and waste.Pythagorean Theorem CalculatorFind the hypotenuse or a missing side of a right triangle with a² + b² = c² — plus the angles, area and perimeter.