10/03/2026
Stair layout starts with one critical measurement: total rise.
In this example, the floor-to-floor height is 9 feet.
9 × 12 = 108 inches of total rise.
If we test 15 equal risers:
108 ÷ 15 = 7.2 inches per riser.
That gives us 15 equal risers and, in this simplified floor-to-floor example, 14 treads.
The important principle is that the total rise must be divided evenly so the stair maintains consistent geometry from bottom to top.
This is an educational geometry example — actual stair design must also satisfy applicable requirements for riser height, tread depth, headroom, landings and other details.
Always calculate the entire staircase before cutting the first stringer.