Glacier vs. Iceberg: What's the Difference?

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Read the comparison below, or explore it visually. Create a visual lesson comparing glacier and iceberg using available credits or plan allowance.

A glacier is a large mass of ice that forms on land from snow compacted over many years and slowly flows under its own weight, while an iceberg is a piece of freshwater ice that has broken off a glacier or ice shelf and floats in the sea or a lake. Every iceberg begins as part of a glacier, but most glaciers never touch the sea.

At a glance

	Glacier	Iceberg
Where it is	On land, in mountain valleys or ice sheets	Floating in the sea or a lake
How it forms	Snow piles up and compacts into ice	Breaks off a glacier's end (calving)
Movement	Flows downhill, centimetres to metres a day	Drifts with currents and wind
Size	Up to whole ice sheets over Antarctica	From car-sized chunks to giant tabular bergs
Lifespan	Can persist for thousands of years	Melts within months to a few years

Which should you use?

Glacier

Call it a glacier when the ice sits on land and flows, such as the Gangotri Glacier that feeds the Bhagirathi river or the Siachen Glacier in the Karakoram.

Iceberg

Call it an iceberg when ice has calved into water and floats free, such as the bergs that drift off Greenland into the North Atlantic, where one sank the Titanic in 1912.

Frequently asked questions

Why is most of an iceberg underwater?

Ice is only slightly less dense than seawater, about 917 kg per cubic metre against roughly 1,025. A floating iceberg displaces its own weight of water, so around 90% of its volume sits below the surface and only about a tenth shows.

Are icebergs made of salt water?

No. Icebergs come from glaciers, which form from snow, so they are freshwater ice. Sea ice is different: it forms when the surface of the ocean itself freezes, and it is much thinner than most icebergs.

Do Himalayan glaciers produce icebergs?

Most Himalayan glaciers end on land and melt into rivers such as the Ganga and Indus. Some end in meltwater lakes, where small chunks break off and float as small icebergs, but they never reach the sea.