Place comparison

Koh Tao compared with Green Island: area, population and density

Koh Tao is about forty percent larger than Green Island, while Green Island reports more registered residents under its township system.

Place A Grouped by country or region Place B Grouped by country or region

Equal-area outline comparison

Outlines are centered and scaled by official land area; position does not show geographic location.

Area

Population

Population density

Area data date

Population data date

The detailed guide below compares Koh Tao with Green Island. Use the selector above to explore any other pair.

Direct answer

How different are Koh Tao and Green Island?

Koh Tao covers 21 km²; Koh Tao's area is 1.39 times Green Island's. Its reported population is 2,531; Koh Tao's population is about 58.5% of Green Island's. By average density, Koh Tao's population density is about 42% of Green Island's.

Area difference

Koh Tao's area is 1.39 times Green Island's 21 km² · 15.1 km²

Population difference

Koh Tao's population is about 58.5% of Green Island's 2,531 · 4,327

Density difference

Koh Tao's population density is about 42% of Green Island's 120.4 /km² · 286.7 /km²

On a familiar scale

Koh Tao ≈ 73% of Matsu (Lienchiang County) 8,309 m² of land per resident
Green Island ≈ 52% of Matsu (Lienchiang County) 3,488 m² of land per resident

Reference scales come from Department of Household Registration, Ministry of the Interior: Land area, households and population density by township and district (year-end 2025) , as of 2025-12-31.

How to read it

This is the closest new small-island comparison: both use a physical island area and a local subdistrict or township population.

Geography and shape

Both islands are compact diving destinations, but Koh Tao has about six additional square kilometres of land. A forty-percent area difference is visible on a common scale without turning either island into a regional giant.

Population context

Green Island has the larger registered population in the current sources. These are resident registers, not daily population: tourists, seasonal workers and people living without local registration can make the number present on the island very different.

Boundaries and definitions

Koh Tao uses the main-island area and Ko Tao subdistrict population, whose administration can include tiny nearby islands. Green Island uses the main island and township population. The pair is well aligned for scale, with a small remaining administrative caveat.

Koh Tao: Physical Koh Tao area paired with the 2024 Ko Tao subdistrict registered population. The administrative subdistrict also covers very small nearby islands, so density is a close local approximation rather than a headcount confined to the coastline.

Green Island: Physical Green Island area paired with the registered population of Green Island Township at year-end 2025. The township and main island are nearly coextensive, but the population remains an administrative count.

In-depth guide

How should Koh Tao and Green Island be understood in context?

Koh Tao and Green Island form a useful small-island pair because their land areas are close enough for a meaningful mental comparison and both have local registered-population data.

The forty-percent land gap in practice

Koh Tao adds about six square kilometres to Green Island area. That is a visible difference, but both remain compact compared with Samui, Pha-ngan, Miyako or Ishigaki.

Coastline shape and steep terrain can make the usable road network diverge even when total area is close.

Resident density is not dive-site crowding

The calculation uses registered residents. Diving visitors, seasonal staff and temporary residents can dominate the population present on a particular day.

Use this result for settlement background, then use visitor, accommodation and transport data for operational planning.

Questions people ask

About this geographic comparison

How much larger is Koh Tao than Green Island?

Koh Tao has about 1.39 times the land area of Green Island, or roughly forty percent more.

Which island has more registered residents?

Green Island in the current official records.

Does density show tourist crowding?

No. It divides registered residents by land area and does not count daily visitors.

Sources

Outline data: