No matter how you call it, stair rails, guardrails, or handrails — some standards must be met when it comes to its height. This height requirement is put forth to ensure the safety of people or workers using these stairs.
International Building Code® (IBC®) Standards
For stairs to be IBC-compliant in height:
1014.2 – Handrail height must not be less than 34 inches (854 mm) or more than 38 inches (965 mm).
1015.3 – Guardrail height must not be less than 42 inches (1,067 mm) in height.
OSHA stair requirements suggest that:
1910.23(e)(2) A stair railing shall be of construction similar to a standard railing, but the vertical height shall be not more than 34 inches nor less than 30 inches from an upper surface of top rail to the surface of tread in line with the face of the riser at the forward edge of the tread.