The floor bearing capacity of a building or of a building module is the maximum amount of weight that the floorplate(s) can safely support. It is usually measured in kilograms per square meter (or pounds per square foot). The supported weight refers to furniture, persons, variable walls, storage contents, etc. It does not refer to any permanent components of the building which are already supported by the floorplate, such as built-in walls, raised floors, mechanical systems, and flooring materials; these must be subtracted from the floor bearing capacity, because the purpose of this measurement is to inform tenants how much extra load they can place on the floor.

The figure describes the extra loading available to occupants after existing permanent loads are accounted for. A floor's total supported weight would include those permanent components as well.

The area unit is part of the measurement: a load per square meter is different from the total weight carried by an entire floor. Movable partitions and stored goods use the available additional allowance.