The largest islands in Indonesia are Sumatra, Java, Kalimantan (Indonesian Borneo). These islands account for over half of the country’s total land area. In fact, these three top contenders represent around 54% of Indonesia’s landmass.
It is a common misconception that Bali or Papua holds this honor. The island group of New Guinea is actually much larger but mostly covered in swampy areas and it doesn’t make the list because it isn’t technically an island! Nevertheless, if we were going to be picky about such details then Java would take out first place with 25 Indonesian provinces under its jurisdiction.
A total of 8,570,000 hectares of land is taken up by Indonesia (a little less than double the size of Japan and China combined). There are about 3 million square kilometers (roughly 1.2 million square miles) of Indonesian territory, but most of that is taken by Borneo and Java.
The most densely populated island is Sumatra with about 7 million people (as of 2013). Java has by far the most people, over 240 million; Irian Jaya has a little more than two million people. Kalimantan also has more than two million people.
The largest island with the most land is Borneo. It is also the third largest island (and third largest country) in area within 10th of the world. The world’s largest island of land is Greenland with about 17.5 million hectares; only two of Indonesia’s smallest islands have more hectares of land: Maluku, 2.7 million hectares, and Flores 2.5 million.