Comparison should be on following facts: 1. Type of building (e.g. Complex / stand alone / High or low rise); 2. Amenities and specifiactions; 3. Completion time and 4. On carpet area basis 5. Developer reputation and projects completed by him in the recent past
Carpet area can be well identified on plans whereas Superbuilt up is perceived based on many common areas of the building. Therefore, the efficiency ratio totally depends upon the planning requirement and its intricacies. However, it's a mathematics which can be calculated after understanding of plans .