A staircase should not only fill a function. It should also be pleasant to use.
Of course you have to adapt to the place you have available but there are some basic rules for a good staircase and it is to adjust the number of steps as well as the height and depth of the steps.
2 Risers + 1 Tread = 63-65 cm. The necessary space to reach these optimal dimensions is not always available, but it's recommended to approach them as much as possible.
A schematic example of a steep and low-transit staircase (2 x 21) + (1 x 21) = 63 cm
Calculate the height of each riser The height of the space is divided by the number of steps for example: 260/15 = 17.33 cm height for each riser
There is no law or requirement of how a staircase should look. The formula should be interpreted as a helper and what one should "take into consideration" exceptions may need to be made for reasons such as location reasons; lot of space = planar staircase, little place = steeper staircase. Plank depth should, however, be approximately 23-25cm.
If you build a curved staircase, the mat is calculated on the walkway, that is, where you are expected to go when using the stairs. Normally this walkway is approx. 35 cm from the outer edge of the staircase.