Residential Floor Area, abbreviated RFA, is the regulated floor area calculation used by the City of Los Angeles to determine whether a project complies with the Baseline Mansionization Ordinance (in non-hillside R1 zones) or the Baseline Hillside Ordinance (in designated Hillside Areas). It is defined in LAMC 12.03 and is significantly broader than the floor area definitions used in other code contexts.

RFA includes more than just enclosed conditioned space. Portions of attics with a ceiling height of more than seven feet count. Rooms with a ceiling height greater than fourteen feet are counted twice. Covered parking is included, with limited exemptions. Basements are included whenever the floor or roof above exceeds two feet above natural grade for non-hillside lots, or three feet above natural grade for sixty percent or more of the basement perimeter on hillside lots.

Detached accessory buildings are included if they exceed two hundred square feet, with a combined cap on exempted accessory buildings of four hundred square feet. Porches, patios, and breezeways with a solid roof are included; lattice roofs are not.