Stair Calculator
Steps, riser height, total run and stringer length from the floor-to-floor rise.
How stair layout works
Divide the total rise by the maximum allowed riser and round UP: that is your number of risers. Divide the rise by that count for the exact riser height, so every step is identical. A 108-inch rise with a 7.75-inch max needs 14 risers of 7.71 inches each. Treads number one fewer than risers because the top step is the upper floor itself.
Code and comfort
Common US residential code: risers max 7 3/4 in, treads min 10 in, and no more than 3/8 in variation between the tallest and shortest riser. The old carpenter's comfort rule: riser + tread between 17 and 18 inches. Always check your local code before cutting stringers.