Stair Calculator – Risers, Treads and Dimensions
Free stair calculator: enter total rise and run to get riser height, tread depth and number of steps. Plan code-compliant stairs for decks, basements and interiors. No sign-up.
Stair Calculator
Enter total rise and run to find the number of risers, treads, and recommended riser height and tread depth. All dimensions in inches.
How the stair calculator works
num_risers = round(total_rise ÷ desired_riser_height)
riser_height = total_rise ÷ num_risers
tread_depth = total_run ÷ (num_risers − 1)
The calculator ensures total rise is met exactly by adjusting riser height. Tread depth is derived from total run.
Designing safe and comfortable stairs
Stairs must balance safety, comfort and space. Risers that are too high cause tripping; treads that are too shallow feel unsafe. Building codes set limits, but within those limits you can optimize. The rule of 18 (riser + tread ≈ 17–18 in) is a useful guideline. For a 7.5 in riser, aim for 10–11 in treads. Consistency matters: every step should have the same riser and tread dimensions.
Measure total rise from finished floor to finished floor. For decks, measure from the surface of the lower deck to the surface of the upper deck. Total run is the horizontal distance the stairs will occupy. If space is limited, you may need steeper stairs (higher risers, shallower treads) or a different layout such as L-shaped or U-shaped stairs. Our concrete calculator helps with footing volume for stair supports.