If the riser height is 7 1/8", what should the number of treads be in a straight-run main stairway?

To determine the number of treads in a straight-run main stairway based on the riser height, it's important to understand the relationship between the riser height and the total rise of the stairway.

The riser height indicates how high each step is from one tread to the next. In this case, with a riser height of 7 1/8 inches, we can calculate the total rise needed for a typical stairway.

A common standard for residential buildings is that the total rise from the floor of the lower level to the upper level is approximately 8 to 10 feet. Let's assume a total rise of 8 feet (which is 96 inches) as a practical example. To find the number of risers (which is equal to the number of treads plus one, because the top landing counts as the escape point), you would divide the total rise by the riser height.

For a total rise of 96 inches with a riser height of 7 1/8 inches (which is approximately 7.125 inches), the calculation would be:

96 inches / 7.125 inches per riser ≈ 13.49 risers

Since you cannot have a fraction of a riser