The 1991 census found that 12.5 million people lived in the Mumbai Metropolitan Region. Of these, 9.9 million lived in Greater Mumbai. Estimates of the present population are in the range of 14 to 15 million.
Bombay's population has grown most rapidly in the years after India's independence. In the decade between the censuses of 1981 and 1991, there have been some signs of a levelling off in the growth. Population figures obtained from historical sources and the Indian census are summarised in the graph and table below.
| Date | Island City | Greater Mumbai | Mumbai Metropolitan Region |
| 1661 | 10,000 | ||
| 1675 | 60,000 | ||
| 1864 | 816,562 | ||
| 1872 | 644,405 | ||
| 1881 | 773,196 | ||
| 1891 | 821,764 | ||
| 1901 | 776,006 | 812,912 | |
| 1911 | 979,445 | 1,018,388 | |
| 1921 | 1,175,914 | 1,244,934 | |
| 1931 | 1,161,383 | 1,268,306 | |
| 1941 | 1,489,883 | 1,686,127 | |
| 1951 | 2,966,902 | ||
| 1961 | 4,152,056 | ||
| 1971 | 5,970,575 | ||
| 1981 | 8,227,382 | ||
| 1991 | 9,900,000 | 12,500,000 |