This is the formula to calculate the carpet area.  Carpet Area = Bedroom area + Living room area + No of balconies + No of toilets - Wall thickness For example, let's say the home has three rooms (350 sq ft, 150 sq ft, 200 sq ft), 3 bathrooms 50 sq ft each, and 3 balconies. Here, the wall thickness is 10 sq ft. So, the carpet area is: =(350 sq ft + 150 sq ft + 200 sq ft) + (3 x 50) + (3) - 10  =(700 sq ft+150 sq ft+3 balconies)−10 sq ft = 850 sq ft and this is the carpet area