Mumbai has a population of roughly 12.8 million people within its city limits and about 21 million across the wider Mumbai Metropolitan Region as of 2025, making it the most populous city in India and one of the largest urban agglomerations on Earth. Those two numbers tell two different stories: the compact administrative core of Greater Mumbai, and the sprawling region of satellite cities that now functions as a single economic engine.
City Versus Metropolitan Region
Greater Mumbai, governed by the Brihanmumbai Municipal Corporation (BMC), covers just 603 square kilometres on a narrow coastal peninsula and holds approximately 12.8 million residents. This is the Mumbai that appears on most population rankings, and it has long topped the list of Indian cities by inhabitants.
The Mumbai Metropolitan Region (MMR) tells a bigger story. Spanning around 6,355 square kilometres, it folds in the satellite cities of Navi Mumbai, Thane, Kalyan-Dombivli, Mira-Bhayandar and Vasai-Virar, pushing the total to roughly 21 million people. When demographers compare Mumbai to other global megacities such as Tokyo, Delhi or São Paulo, it is usually this metropolitan figure they are using. Together the region produces a strikingly large share of national output: Mumbai alone generates close to 6% of India's GDP, handles a large portion of the country's maritime trade and hosts both the Bombay Stock Exchange and the Reserve Bank of India.
One of the Densest Cities on Earth
Population matters less than how it is packed in, and Mumbai is packed in tightly. Greater Mumbai averages around 21,200 people per square kilometre, but that figure conceals extremes. The historic island city — neighbourhoods such as Fort, Colaba and Malabar Hill — exceeds 30,000 people per square kilometre, while pockets of central Mumbai like Dharavi, Kurla and Byculla reach localised densities estimated at 100,000 or more.
Dharavi, frequently described as one of Asia's largest informal settlements, illustrates the scale: an estimated 700,000 to 1,000,000 people live on roughly 2.1 square kilometres. Yet it is far from idle, sustaining a vibrant informal economy of leather, pottery, textiles and recycling. Overall, an estimated 40% of Mumbai's residents — perhaps five million people — live in slums or unauthorised housing, often within sight of some of the most expensive real estate on the planet.
A Century of Explosive Growth
Mumbai's population has multiplied many times over in living memory. The city counted about 1.5 million people in 1941, climbed to roughly 6 million by 1971, and reached around 12 million by 2001. Migration was the engine: people from across Maharashtra, Uttar Pradesh, Bihar, Gujarat, Rajasthan and the southern states arrived in search of work, and the city long absorbed hundreds of new arrivals every day.
That momentum has shifted. Within the city limits, growth has slowed sharply because Mumbai has become extraordinarily expensive — prime South Mumbai property rivals the priciest markets in the world. As a result, expansion has migrated outward to the satellite cities of the MMR, which have been growing at 3 to 4% annually. Planners project the metropolitan region could approach 28 million people by 2036, prompting major infrastructure investments including new Mumbai Metro lines and the 22-kilometre Mumbai Trans-Harbour Link connecting the island to Navi Mumbai.
Who Lives in Mumbai
Mumbai is a microcosm of India's diversity. Native Marathi speakers make up roughly 40% of residents, followed by sizeable Gujarati and Hindi-Urdu speaking communities, South Indians and smaller groups from virtually every state. Religious demographics broadly mirror the national picture, with a Hindu majority of around two-thirds, a substantial Muslim minority of about one-fifth, and notable Buddhist, Jain and Christian populations.
The median age sits near 30 years, reflecting India's youthful profile, and the city's social fabric runs from financial professionals in Bandra-Kurla Complex to the Koli fishing communities along the coast, from Bollywood's stars in Juhu to the famed dabbawalas who deliver some 200,000 lunches a day. Binding it all together is the suburban railway, the busiest commuter rail network in the world, carrying over 7.5 million passengers daily. If you enjoy testing your knowledge of world cities and populations, try our interactive geography games.
Frequently Asked Questions
What is the population of Mumbai in 2025?
Mumbai's population is approximately 12.8 million within the city limits of Greater Mumbai and around 21 million across the Mumbai Metropolitan Region as of 2025.
Is Mumbai bigger than Delhi?
Within municipal limits Mumbai is India's most populous city. Measured by full metropolitan area, however, the Delhi region is larger, so rankings depend on whether you count the city core or the wider urban agglomeration.
Why is Mumbai so densely populated?
Mumbai sits on a narrow reclaimed peninsula with very limited room to expand, while drawing decades of economic migrants. Constrained land plus relentless inflow has produced one of the highest urban population densities anywhere in the world.
How fast is Mumbai's population growing?
Growth inside the city core has slowed because of high costs, but the surrounding satellite cities are expanding at 3 to 4% a year, and the metropolitan region is projected to near 28 million people by 2036.
