Why does an iceberg's submerged fraction only depend on density, not size?

Archimedes' principle says a floating object displaces water weighing exactly as much as itself. Since weight is density times volume times gravity for both the ice and the displaced water, the volume terms scale together and cancel out — leaving submerged fraction = ice density / water density, independent of how big the iceberg is.

Why is about 90% of an iceberg underwater?

Glacial ice is roughly 850-920 kg/m³ depending on trapped air bubbles, while seawater is about 1025 kg/m³. Dividing ice density by water density gives roughly 0.88-0.90, so about 88-90% of the iceberg's height stays submerged and only the tip pokes above the surface.

Does a calved ice chunk float at a different depth than the main iceberg?

No — since the chunk is made of the same ice, it settles at exactly the same submerged fraction as the main iceberg once it stops bobbing, regardless of how large or small the chunk is.

Home▸Physics & Mechanics▸Iceberg Buoyancy Physics (2D)

Iceberg Buoyancy Physics (2D)

A 2D side-view iceberg: drag ice density and water density and watch the submerged fraction recompute live from Archimedes' principle, then trigger calving and watch each chunk settle at the same equilibrium depth as the main berg.

Physics & Mechanics2DModerate60 FPS📱 Mobile-adapted⇄ 3D version

An iceberg floats because ice is slightly less dense than seawater, and by Archimedes' principle it must displace a volume of water weighing exactly as much as itself. Since weight is density times volume times gravity for both the ice and the water it displaces, the volume terms cancel and the submerged fraction reduces to a single ratio: ρ_ice/ρ_water — independent of how big the iceberg is. This 2D side-view companion lets you drag ice density and water density directly and watch that fraction, and the freeboard height above the surface, recompute live, then trigger a calving event and watch a chunk break away, fall, and settle at the exact same equilibrium depth once it hits the water, since it's made of the same ice.

⚙ Under the hood

A 2D side-view companion: sliders set ice density, water density, iceberg height and wave choppiness, and the submerged fraction recomputes live as ρ_ice/ρ_water; calved chunks fall and settle at that same fraction.

buoyancyarchimedes principledensityicebergcalving2d

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install