Question 1

How to calculate stairs?

Accepted Answer

To calculate stairs, you need the floor-to-floor height and available run length. Divide the height by the optimal rise (about 18 cm) to get the step count. The run depth is calculated using the step formula: 2 x rise + run = 63 cm.

Question 2

What is the step formula?

Accepted Answer

The step formula (Schrittmassregel) is: 2h + r = 63 cm, where h is the rise height and r is the run depth. The value 63 cm corresponds to the average stride length of an adult. An acceptable range is 59 to 65 cm.

Question 3

What is the maximum riser height?

Accepted Answer

According to DIN 18065, the maximum riser height in residential buildings is 20 cm (minimum 14 cm). In public buildings, the maximum is 19 cm. For attic and secondary stairs, up to 21 cm is allowed. The ideal rise is about 17 to 18 cm.

Question 4

What is the minimum stair width?

Accepted Answer

Minimum stair width depends on usage. Residential buildings with up to 2 units: at least 80 cm, with more units: 100 cm. Public buildings: at least 125 cm. A width of 90 cm is recommended for homes.

Question 5

What does DIN 18065 say?

Accepted Answer

DIN 18065 is the German standard for building stairs. It specifies dimensions for rise (14-20 cm), run (23-37 cm), minimum widths, handrail heights and headroom. The standard distinguishes between residential, public and secondary stairs.

Question 6

How many steps do I need?

Accepted Answer

The number of steps is the floor height divided by your desired rise height. For a floor height of 270 cm and a rise of 18 cm, you need 15 steps (270 / 18 = 15).

Question 7

What is the ideal slope angle?

Accepted Answer

The ideal slope angle for residential stairs is between 30 and 37 degrees. Shallower stairs (under 30 degrees) use too much space, steeper stairs (over 38 degrees) become uncomfortable. Ladder stairs can be up to 45 degrees.

Question 8

How to calculate a spiral staircase?

Accepted Answer

For spiral staircases, the run depth is measured at the walking line (about 2/3 of the tread width from the inner edge). The rise stays the same, but treads vary: narrower inside, wider outside. The minimum tread at the inner edge must be at least 10 cm.

Question 9

What is the difference between rise and run?

Accepted Answer

The rise (h) is the vertical height of a single step - the distance between two tread surfaces. The run (r) is the horizontal depth of the tread surface - the distance between two step nosings. Together they determine the comfort of the staircase.

Question 10

How much space does a staircase need?

Accepted Answer

Space requirements depend on the stair type. A straight staircase with 270 cm floor height needs about 3.5 to 4.5 m of run length. A quarter-turn saves about 1 m, while half-turn or spiral stairs need even less floor area.

Guide: Staircase Calculator

Calculate Stairs: Rise, Run & Building Code Explained

Step Formula: The Most Important Rule for Stairs

DIN 18065: Staircase Standards for Residential Buildings

Winding Staircase: Quarter-Turn and Half-Turn Calculation

Staircase Costs: How Much Does a New Staircase Cost?

Staircase Renovation: Costs and Options