The carpet area is the most important type of area buyers should consider when purchasing a flat because it represents the actual usable space available inside the home. It includes the floor area of bedrooms, living rooms, kitchens, and bathrooms but does not include external walls, balconies, terraces or common spaces such as lifts and staircases. Buyers should also understand what is RERA carpet area, as it is the legally defined measurement used for registered real estate projects. The RERA carpet area includes the area covered by internal partition walls but excludes external walls, service shafts, balconies, verandahs and open terraces. The main difference between RERA carpet and actual carpet is that actual carpet area may be calculated differently by builders, while RERA carpet area follows a standard legal definition. When comparing properties, buyers may also ask what is built up area and what is super built up area.