The lobby height for a building is the maximum vertical distance between floor and ceiling at any one point in the shared entrance, reception, or gathering space.

The lobby must be a room or space with direct access to the main entrance - that is, without need of passing through a fire stairwell or taking an elevator. It should generally be freely accessible from the entrance, either at the same level or on an adjacent floor, although it may be separated from the main entrance by a vestibule, airlock, weather door, security checkpoint, or other necessary, formal, or ornamental barrier.

This measurement is intended mainly for lobbies in public buildings, office buildings, apartment buildings, hospitals, and other buildings shared by many people, which have medium to large spaces for reception, gathering, meeting, waiting, registration, orientation, and similar purposes. It does not generally apply to foyers of private homes or to simple entrance areas.

A lobby's height may extend over multiple floors if such a continuous vertical space is open within the lobby. However if the space meets or exceeds 5 actual floor levels, it should be listed as an atrium height instead.