Calculate stair step count, riser height, and tread depth from floor height: follows standard Blondel formula 2R + T = 600–640mm for natural, safe movement.
The most comfortable stair step dimensions are governed by Blondel formula: 2h + b = 600–640mm, where h is the riser height and b is the tread depth. 600–640mm approximates standard human walking pace stride length.
R is the riser height, and T is the tread depth. The sum of twice the riser plus the tread (2R + T) corresponds to the average human stride length on flat ground (600–640mm). Stairs adhering to this formula ensure natural gait, minimizing fatigue and trip hazards.
This range provides comfortable step elevation for adults in residential architecture. Risers below 150mm extend total stair length, consuming excess floor space; risers above 180mm cause rapid fatigue and steep ascent.
Enter floor-to-floor height in millimeters (mm) — for example, 3.3 meters should be entered as 3300 mm for millimeter precision.
No. This is a rapid ergonomic reference. Construction drawings require structural review regarding stair width, landings, handrails, and local building codes.