1. Floor Space Index (FSI) / Floor Area Ratio (FAR)

The Floor Space Index (FSI), also known as Floor Area Ratio (FAR), is a critical metric that dictates the total permissible built-up area on a plot. It is calculated using the formula 

FSI = Total Built-up Area / Plot Area 

For instance, if a plot has an area of 1,000 sq. ft. and the permissible FSI is 1.5, the maximum allowable built-up area would be 

1,000 sq. ft. × 1.5 = 1,500 sq. ft. 

FSI values vary based on factors such as location, zoning regulations, and the type of building (residential, commercial, etc.) . 

2. Plot Coverage and Setback Regulations

Plot coverage refers to the portion of the plot area that can be occupied by the building’s footprint, while setbacks are the minimum open spaces to be maintained around the building. These parameters ensure adequate light, ventilation, and privacy. 

For example, in Chennai, the Chennai Metropolitan Development Authority (CMDA) stipulates that for special buildings, the maximum permissible plot coverage is 65%, meaning that 35% of the plot must remain open 

Setback requirements vary based on building height and plot size, and they are crucial in determining the actual buildable area on the plot 

3. Local Development Control Regulations

While the National Building Code provides general guidelines, local municipal authorities have specific Development Control Regulations (DCRs) that detail permissible FSI, plot coverage, setbacks, and other construction norms. These regulations can vary significantly between different cities and even within zones of the same city.​ 

For instance, in Delhi, the permissible FAR can range from 1.2 to 3.5, depending on the plot size and location . Therefore, it’s essential to consult the local DCRs to determine the exact buildable area for a specific plot.