Initial data
The height of the stairs 2500 mm
The length of the stairwells in the plan 3000 mm
Number of steps 13
The thickness of the treads 50 mm
Tread Overhang 50 mm

Open string stairs
The length of the open string 3873 mm
The angle of the stairs 39.8°

Step size
Step height 192 mm
Depth steps 281 mm
The height of risers 142 mm