Overview

This article explains how islands are ranked by surface area and why different lists may vary. A conventional list of islands by area arranges landmasses that are entirely surrounded by water from largest to smallest. Many published tables apply a lower cutoff (for example, 250,000 km²) to limit the number of entries. For an accessible starting point see a general list of islands.

Definitions and criteria

What counts as an island depends on definitions. In general, an island is a piece of land completely surrounded by water at normal sea levels. Some definitions exclude land masses commonly classified as continents. For instance, whether to treat Australia as a continent or the world’s largest island is debated in casual discussion; if Australia is excluded, Greenland is typically recognized as the largest island. Regional concepts such as Australasia affect broader geographic groupings but do not change basic island-area rankings.

Examples: the largest islands

Although exact figures vary by source and measurement method, the islands most often listed at the top are:

  • Greenland — commonly listed as the largest island when Australia is treated as a continent.
  • New Guinea — divided politically between two countries; notable for high biodiversity.
  • Borneo — shared by multiple nations and known for extensive rainforests.
  • Madagascar — an island with exceptional endemic flora and fauna.
  • Baffin Island — one of the largest Arctic islands with rugged terrain.

Measurement issues and variations

Lists differ because of mapping precision, inclusion of inland water in area totals, tidal flats, and whether land bridged by human structures remains an island. River islands, deltaic islands and seasonal islands also present classification challenges. Standard references use consistent cartographic data but still note small discrepancies between editions.

Importance and uses of the ranking

Ranking islands by area is useful for geographic education, environmental assessment and comparative studies of population density, resource distribution and conservation priorities. Large islands often host unique ecosystems and significant human populations, making accurate area data important for planning, research and international comparisons.