Kangaroo Island is about 4,400 square kilometres in area and roughly 150 km long from east to west, making it Australia’s third‑largest island after Tasmania and Melville Island.

Quick size snapshot

  • Area: about 4,405 km² (around 1,700 square miles).
  • Length: about 145–150 km east to west.
  • Width: up to about 54–57 km at its widest, narrowing to around 1 km at its narrowest point.
  • Coastline: roughly 500+ km of coast.

How that compares

  • Much bigger than many people expect: it’s about 75 times larger than Manhattan and vastly larger than typical “day‑trip” islands like Rottnest Island in Western Australia.
  • It is also far larger than the entire land area of the Maldives, which makes Kangaroo Island more like a small region or province than a tiny resort island.

Travel sense of scale

  • Driving end to end and exploring properly usually takes several days; many tourism operators recommend 4–5 days so you are not rushing from sight to sight.
  • With only around 5,000 residents spread over this large area, it feels spacious and wild despite its substantial physical size.

TL;DR: If you’re wondering “how big is Kangaroo Island?” think of a large, sparsely populated island region: about 4,400 km², 150 km long, and big enough that it deserves a multi‑day trip rather than a quick look.

Information gathered from public forums or data available on the internet and portrayed here.