What is the approximate volume of Earth's oceans in cubic kilometers?

The approximate volume of Earth's oceans is 1.332 billion cubic kilometers. This estimate represents the combined water held in the connected global ocean, rather than the volume of one particular ocean basin.

Scientists estimate ocean volume by combining detailed maps of the seafloor with measurements of ocean area and depth. A widely cited calculation gives an average ocean depth of about 3,682 meters and an ocean-covered area of roughly 361.8 million square kilometers. Multiplying those values produces the 1.332-billion-km³ estimate.

The figure is approximate because seafloor mapping is continually improving, and different definitions of ocean water can produce slightly different totals. Some references round the volume to 1.335 billion km³. A common mix-up is confusing ocean volume with all of Earth's water: including glaciers, groundwater, lakes, rivers, and atmospheric water raises the total to about 1.386 billion km³.

The oceans cover about 71% of Earth's surface and contain roughly 97% of its water.