Enter the height and run of your stairs to find the rise of each step, the stringer length, the angle, and more.
Everything is calculated live as you type. Answers are shown in feet and inches, and in centimeters.
List the choices that keep each step between 5 and 10 inches high, for a given total rise and run.
The total rise is the height from the lower floor to the upper floor. The rise of a step is the height of one step, and the run is its depth. The stringer is the sloping board that holds the treads and risers. A staircase with N steps has one more riser than it has runs, because the top step is the upper floor itself.
With a fixed rise, it divides the total rise by the rise you want and rounds up to a whole number of risers. The first step may be shorter than the rest, and the result shows its height. With a fixed number of steps, every rise is the same. The stringer height is the total rise less one rise, and the stringer length follows from the Pythagorean theorem using that height and the total run. The angle is the arctangent of rise over run.
If the treads have thickness, the first step is shorter by that thickness, and the stringer is cut lower by the same amount. The headroom check finds the height of the stairs under the start of the floor opening and measures what is left below the underside of the upper floor. If the headroom is too small, the result says how long the opening has to be. A flush mount puts the stringer against the upper floor with a run for every riser, so the stringer height equals the full rise.
Many building codes limit the rise to about 7 3/4 inches and ask for a run of at least 10 inches, with a headroom of 6 feet 8 inches. The basic version lists the choices with a rise between 5 and 10 inches. Check the codes where you live, since they differ, and have a qualified builder check your plan.
Divide the total rise, the height between floors, by the number of risers. For 105 inches and 15 risers, each rise is 7 inches.
There is one more riser than there are runs. A staircase with 15 risers has 14 treads on the stringer, because the upper floor works as the last tread.
The stringer is the sloping board, usually cut from lumber, that supports the treads and risers. Most stairs use two or three.
Most home stairs are between about 30 and 37 degrees. Stairs steeper than about 42 degrees are hard to climb safely.
It means the stringer is fastened flush with the top of the upper floor, so the number of runs equals the number of risers and the stringer height equals the total rise.
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