Initial data
The height of the stairs 2.5 m     (2500 mm)
The length of the stairwells in the plan 3 m     (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 3.873 m     (3873 mm)
The angle of the stairs 39.8°

Step size
Step height 0.192 m     (192 mm)
Depth steps 0.281 m     (281 mm)
The height of risers 0.142 m     (142 mm)