Why some of the IITs such as IIT-M IIT-B are still called as IIT Madras & Bombay even though the cities have been changed to Chennai and Mumbai?

IIT Bombay and IIT Madras were established in 1958 and 1959 respectively. Both these institutions have emerged as highly renowned centers of Engineering studies in India. Both IIT Bombay and IIT Madras are more than an institution, they are in fact a brand with a high relevance and strong network in the industry. 

The ‘Bombay’ or ‘Madras’ is a part of this brand name. This is not the address of these institutions, as both these cities have long been renamed as Mumbai and Chennai respectively. The institution name has not been altered because of the prestige and legacy carried by both these titles. 

Thus, IIT Bombay and IIT Madras haven’t been renamed over the years.

IITs have built a reputation among top universities and companies both within and outside India. The reputation is linked with the name of the Institute and hence a change of name will affect the reputation of the Institute. 

To make it simpler, IITB is famous even outside India but if its name is changed to IITM (Mumbai) then people who are unaware of the new name will not be convinced of the institute's credibility. Similarly, the admission application of an IIT Madras student will lose its credibility if instead of Madras the institute's name is written as IIT Chennai. This is because the latter is not known to many.

To maintain the credibility of the Institute, and stop any kind of misunderstandings the name has not been changed.