The architectural volume of a building is the total cubic area enclosed within its perimeter, not including open balconies or arcades, or areas behind permanently open screens. Only the above-ground portion of a building is included (i.e. everything above the base). This includes all solids and voids belonging to the enclosure of a building: inner and outer walls, facade elements, etc.; but does not include the volumes of projecting exterior walls, solid spires, or other such extensions.

The perimeter of a building includes any adjacent wings which are not counted as separate structures. Garages are included only if they are reasonably well screened or walled-in; moderate wall openings do not disqualify a garage's inclusion, but fully open garages are treated like balconies.

A volume of this kind is calculated from the building's own dimensions rather than measured, so it follows whichever outline the source used. A figure taken to the facade and one taken to the structure differ, and neither is wrong as long as the record says which.

It is not a floor area multiplied by a height. A building whose upper floors step back has less volume than that calculation gives, which is why the two figures disagree for most towers.