Shape of the building plan (often referred to as "footprint") is the shape of the projection of the exterior edge of the building at grade onto the horizontal plane. To the extent possible, it is classified according to various simple shapes and letters of the alphabet. The shape from the table that most closely resembles the shape of the building footprint should be listed.

Where the building changes in plan cross-section (such as in the case of tower and podium, or a setback) some judgment is called for – in general, the shape that the building conforms to for the majority of its height should be listed, and may differ from the footprint (plan cross-section) at ground floor level.