According to Occupational Safety and Health Administration (OSHA) requirements in the U.S., the majority of stair handrails must be between 30 and 37 inches in height. The measurement is from the upper surface of the handrail to the surface of the tread, which is in line with the face of the riser at the forward edge of the tread.
In residential homes, the standard height recommendation is 30 inches. There is leeway to adjust this height according to the height of the home's occupants. Local building codes can affect placement of the handrail, sometimes based on the type of structure involved. Commercial buildings require a safety inspection, preferably before installing the proposed handrails.