How much vertical space does one rack unit (RU) occupy?

One rack unit (RU) occupies a vertical space of 1.75 inches, which is equivalent to approximately 44.45mm. While the answer given cites 45mm, it's important to recognize that this aligns closely with the official measurement of a single rack unit. This measurement is crucial in data center design and equipment layout, as it dictates both the physical organization of equipment in racks and the space allocation for cooling, power management, and service access.

In the context of equipment installation and maintenance, understanding this unit of measure (RU) is essential for ensuring that devices fit correctly within racks and that efficient airflow and accessibility are maintained. Other options listed do not provide an accurate conversion or measure pertaining to how much vertical space one rack unit occupies.