The most densely populated islands of 50 km² or more are Salsette Island, the island Mumbai is built on, and Manhattan, level at roughly 28,000 to 30,000 people per km²: about 29,800 for Salsette (18.9 million people on 635 km²) and 28,500 for Manhattan, on the JRC's 2025 population grid. Hong Kong Island is third at 14,800, then São Vicente Island in Brazil (11,700) and Xiamen Island in China (11,700), which are level, and Mactan in the Philippines (9,700) with Singapore's main island (9,600). Salsette's figure is a grid estimate, because India has not counted its people since 2011. Much smaller islands are more crowded still, but they are too small for the grid, so we give them separately from census counts: Malé in the Maldives has 66,800 people per km².
The measurement problem comes first
Most lists of crowded islands mix a city's population from one source with an island's area from another, and the two rarely cover the same ground. We measured every island the same way instead. The islands come from the USGS Global Islands database, which traces the world's shoreline at 30 m from 2014 Landsat imagery and lists 22,471 islands larger than 1 km². People come from GHS-POP, the European Commission Joint Research Centre's population grid, which spreads census counts over 1 km cells according to how much housing satellites see in each, and scales them to UN estimates for 2025. We laid all 6,835 islands of 10 km² or more over that grid.
The difficulty is the coast. A 1 km cell on a narrow strait holds land on both sides, and the grid does not say which side its people live on. We split each shared cell by land area, using the JRC's own land layer, and also worked out two limits: the density if every shared cell went wholly to the island, and if shared cells counted for nothing. On Hong Kong Island, 15 of the 120 cells the island touches also hold other land.
Size decides how much that matters. For islands between 10 and 50 km² with at least 100,000 people, the two limits sit a median 34% apart, though only six islands fall in that group; above 50 km² the median gap is 6%. So the ranking covers islands of 50 km² or more with at least 100,000 people: 249 in the USGS data, of which we set aside four where one cell holds over 25% of the island's people, a sign that the grid has piled a whole census district onto one spot. A simpler count that gives each cell wholly to the island holding its centre moves none of the top 13 by more than 9%, and only swaps islands that are already level.
| Rank | Island | Main city | Country | Area, km² | People, 2025 | People per km² | Range per km² |
|---|---|---|---|---|---|---|---|
| =1 | Salsette Island | Mumbai | India | 635 | 18,906,000 | 29,800 | 29,100–29,900 |
| =1 | Manhattan | New York City | United States | 55 | 1,565,000 | 28,500 | 23,400–32,100 |
| 3 | Hong Kong Island | Hong Kong | Hong Kong, China | 83 | 1,231,000 | 14,800 | 13,300–15,100 |
| =4 | São Vicente Island | Santos | Brazil | 60 | 703,000 | 11,700 | 11,100–12,200 |
| =4 | Xiamen Island | Xiamen | China | 142 | 1,661,000 | 11,700 | 11,500–11,800 |
| =6 | Mactan | Lapu-Lapu | Philippines | 61 | 585,000 | 9,700 | 9,300–9,900 |
| =6 | Singapore Island | Singapore | Singapore | 634 | 6,064,000 | 9,600 | 9,500–9,600 |
| 8 | Nantai Island | Fuzhou | China | 124 | 753,000 | 6,100 | 5,400–6,800 |
| 9 | Abu Dhabi Island | Abu Dhabi | UAE | 95 | 519,000 | 5,500 | 5,300–5,600 |
| 10 | Vũng Tàu | Vũng Tàu | Vietnam | 71 | 367,000 | 5,100 | 5,000–5,500 |
| =11 | Batam | Batam | Indonesia | 394 | 1,576,000 | 4,000 | 3,800–4,100 |
| =11 | Muharraq Island | Muharraq | Bahrain | 66 | 261,000 | 4,000 | 3,400–4,200 |
| 13 | Vypin Island | Kochi | India | 62 | 214,000 | 3,400 | 3,000–3,700 |
Salsette Island and Manhattan, level at the top
The shoreline data draws Mumbai's old island city and Salsette as one island of 635 km², running from the city's southern tip north to Thane and Mira-Bhayandar. The grid puts 18.9 million people on it, 29,800 per km², with limits of 29,100 to 29,900.
That number is a model. India's last census, in 2011, counted 12,442,373 people in Greater Mumbai (3,085,411 in the Mumbai City district and 9,356,962 in Mumbai Suburban), all of it on Salsette. Spread over the whole island, that alone is 19,600 per km², before adding Thane and Mira-Bhayandar or fourteen years of growth. The grid's higher figure partly reflects the JRC's method, which, as its data package explains, scales big cities to the UN's urban projections.
Manhattan needed different handling. The USGS shoreline does not separate it from the mainland, so we took its outline from New York City's own borough boundaries, which follow the shore, kept the main island (54.9 km²) and measured it on the same grid. It gets 1.56 million people, 28,500 per km², with wide limits of 23,400 to 32,100 because many of its cells also hold land across the rivers. The Census Bureau's July 2025 estimate for the whole borough, small islands included, is 1,664,862 people on 58.7 km² of land, 28,400 per km². Salsette's range sits inside Manhattan's, so we rank them equal first. Both are about twice as dense as anywhere else on the list: even their low limits, from 23,400, clear every other island's high limit, at most 15,100.
Hong Kong Island, and the harbour
Hong Kong publishes figures for an area that is almost exactly the island. The Census and Statistics Department's district table gives the Hong Kong Island region 1.16 million people in mid-2025 on 79.93 km², or 14,540 per km². Our grid figure is 1.23 million (+6%), and our density, 14,800, is within 2% of the official one. The shoreline data folds the small island of Ap Lei Chau into Hong Kong Island, so its people are counted here.
São Vicente and Xiamen: too close to separate
São Vicente Island, shared by the cities of Santos and São Vicente on Brazil's São Paulo coast, has about 703,000 people on 60 km². Brazil's 2022 census counted 418,608 in Santos and 329,911 in São Vicente (IBGE table 4709), 748,519 together, but both municipalities also reach onto the mainland.
Xiamen Island comes out 0.3% behind on the grid, with 1.66 million people on 142 km². The official count is much higher: Siming and Huli, the two districts on the island, had 2.07 million residents at the end of 2024, according to the Xiamen Statistics Bureau's sample survey as reported by The Paper, 25% more than the grid. On the same area that is 14,600 per km², level with Hong Kong Island. We cannot tell which source is closer, so Xiamen could be third rather than fourth.
Mactan and Singapore
Mactan, across a narrow channel from Cebu City, has about 585,000 people on 61 km². The 2020 census counted 497,604 in Lapu-Lapu City and 70,595 in Cordova, which share the island (568,199 together, as republished by PhilAtlas), 3% below a grid estimate five years newer.
Singapore's main island is 1.0% behind Mactan, another tie. The grid puts 6.06 million people on its 634 km²; the Department of Statistics counted 6.11 million in the whole country in June 2025, a difference of −0.8%. Its official density, 8,300 per km², is lower than ours because it divides by all 735.7 km² of national land, including smaller islands and land reclaimed since 2014. More on its size is in how big Singapore is.
Fuzhou, Abu Dhabi, Vũng Tàu and the Gulf
Eighth is Nantai Island in the Min River at Fuzhou, which the shoreline data separates from the mainland: 753,000 people on 124 km², 6,100 per km². Abu Dhabi Island follows at 5,500, then the Vũng Tàu headland in Vietnam, which the shoreline data cuts off as an island, at 5,100. Batam, the Indonesian island facing Singapore, holds 1.58 million people at 4,000 per km², level with Muharraq Island in Bahrain (66 km², 4,000). Vypin Island at Kochi completes the list.
Staten Island, next at 3,200, is a good test of the method, because the island is a single county. We estimate 488,000 people on 151 km²; the Census Bureau's July 2025 estimate is 501,290 on 149.0 km² of land, −2.6% from ours.
Big islands sit far down the list. Java, the most populous island on the grid at 149.9 million people, averages 1,176 per km² over 127,467 km², the highest of any island over 10,000 km², ahead of Taiwan at 657. Its provinces and volcanoes are covered in our Java island guide.
Smaller than the grid: Malé and Santa Cruz del Islote
The famous answers to this question are islands too small for a 1 km grid. Malé covers 2.06 km² in the Maldives Bureau of Statistics' census table, which counted 137,238 residents there in 2022: 66,800 per km², 2.2 times Salsette. The capital's other wards are separate islands: Hulhumalé had 65,714 people on 4.14 km², and Villingili 6,755.
Santa Cruz del Islote, off Colombia's Caribbean coast, is denser again: a community census reported by El Tiempo in April 2020 found 779 people on about one hectare, roughly 78,000 per km². Neither the area nor the count is official, and other reports give different numbers, so treat it as an order of magnitude.
| Island | Country | People | Area, km² | People per km² | Count |
|---|---|---|---|---|---|
| Santa Cruz del Islote | Colombia | 779 | about 0.01 | about 78,000 | Community census, reported April 2020 |
| Malé | Maldives | 137,238 | 2.06 | 66,800 | Census 2022 |
One island falls between the two lists. Petit-Bassam, a 31 km² island in the lagoon at Abidjan, Côte d'Ivoire, gets 985,000 people on the grid (31,700 per km²), but its limits run from 21,100 to 35,300. The 2021 census counted 732,895 in the three communes on the island, Treichville (106,552), Marcory (214,061) and Koumassi (412,282), as listed by citypopulation.de: about 23,600 per km², which suggests the grid is around 34% too high there. Even so, it would rank behind the top two.
The island table and its sources
Densities are people per km² of land, with the population a 2025 estimate and the area from the 2014 shoreline (Manhattan's from the city's current outline); reclaimed land added since is missing. You can download the data as a CSV with the top 100 islands, their country, area, 2025 population, density and the low and high limits; to scatter area against density for the islands you care about, Parity makes that chart from the spreadsheet in a couple of clicks. For the country-level picture, see our ranking of the countries with the highest population density, or compare these islands with the largest islands in the world.
- European Commission JRC, GHS-POP R2023A, epoch 2025, 1 km Mollweide grid: © European Union, CC BY 4.0 (reuse authorised with acknowledgement); 2025 is a model estimate built on census data and UN projections; doi:10.2905/2FF68A52-5B5B-4A22-8F40-C41DA8332CFE
- European Commission JRC, GHS-LAND R2022A (land area per 1 km cell, 2018): © European Union, CC BY 4.0
- USGS, Esri and UNEP-WCMC, Global Islands (Sayre 2023), Big Islands layer: U.S. public domain; 30 m shoreline from 2014 Landsat imagery; queried from the USGS ArcGIS service
- Hong Kong Census and Statistics Department, table 110-02001 (mid-2025)
- Singapore Department of Statistics, table M810001 (June 2025)
- U.S. Census Bureau, county population estimates (Vintage 2025) and 2020 Gazetteer land areas
- IBGE, 2022 Census, table 4709
- NYC Department of City Planning, Borough Boundaries (water areas excluded), NYC Open Data: Manhattan's shoreline; NYC Open Data states there are no restrictions on the use of Open Data; no separate licence is given for the dataset
- Institut National de la Statistique (Côte d'Ivoire), RGPH 2021 commune populations, via citypopulation.de
- Maldives Bureau of Statistics, Statistical Yearbook 2024, table 1.5 (Census 2022)