The Door Has to Borrow Space Somewhere
A restroom entrance needs room for its door to swing. If it opens outward, that space comes from the hallway: someone stepping out can sweep the door into a passerby, a wheelchair, or a line of people. In a busy building, keeping the swing inside can make the corridor easier and safer to use.
The tradeoff is that an inward-opening door takes up floor area inside the restroom. Designers can often accommodate that in a shared restroom, where the entrance opens into a larger room rather than directly into a narrow stall. The door’s position and the room’s layout must leave enough usable space for people to enter and move around it.
It’s a Layout Choice, Not a Universal Rule
The direction is not always inward. An outward swing can be important when the room is too small for the door to open without trapping someone behind it, and accessibility or building-code requirements can affect the design. For example, a stall door may open outward so a person inside has more room.
So the familiar inward swing often reflects a simple compromise: protect the shared hallway by using space within the restroom. Where that space is scarce—or safe exit requires a different arrangement—the door may swing the other way.
