Stair Calculator
Enter the total height to climb, your target riser height, and tread depth to find the number of steps and the stair's dimensions.
How stair dimensions are calculated
The number of steps is the total height divided by your target riser height, rounded to a whole number — since you can't have a fraction of a step, the actual riser height is then recalculated by dividing the total height evenly across that whole number of steps.
A staircase with N steps has N risers but only N−1 treads (the top step usually lands on the floor above, which doesn't need its own tread). Total run is the number of treads times the tread depth, and the stair angle is found from the actual riser and tread depth using the arctangent function.
Frequently asked questions
What's a comfortable riser height for stairs?
Common residential building guidance suggests risers around 15-20 cm (roughly 6-8 inches), with a well-known rule of thumb being that 2× riser + 1× tread should total around 60-65 cm for comfortable stairs.
Why does the actual riser height differ from my target?
Since the number of steps must be a whole number, the exact riser height is recalculated to evenly divide the total height — your target is just a starting point to find a sensible number of steps.
What's a typical stair angle?
Most residential stairs fall between about 30-35 degrees — steeper than that starts to feel uncomfortably steep, and much shallower requires a lot of horizontal space.