Handrail Height Calculator
Handrail height per US residential code (IRC): 34 in - 38 in above the nosing, measured vertically.
Ramp Slope Calculator
ADA maximum ramp slope is 1:12 (8.33%), meaning at least 12 in of run for every 1 in of rise.
Stair Riser Calculator
IRC-standard comfortable riser height is 7 in - 7.75 in (7.75 in is the US residential code maximum). Number of risers = round(total rise / target riser).
Stair Stringer Calculator
Stringer (diagonal) length = sqrt(total rise² + total run²) — the Pythagorean theorem. Stringer count follows 1 per ≤36 in of stair width, minimum 2.
Stair Tread Calculator
Number of treads = number of risers - 1. Code minimum tread depth is 10 in; the comfort rule of thumb targets 2 x riser + tread ≈ 24-25 in.
Wheelchair Ramp Calculator
Per ADA 1:12 maximum slope, minimum ramp run = rise x 12. A 5 ft flat landing is required at least every 30 ft of ramp run.