The short answer: Earth's ocean weighs about 1.4 x 10^21 kilograms (roughly 1.4 sextillion kilograms, or about 3.1 x 10^21 pounds). That comes from the total ocean volume multiplied by the average density of seawater.
Ocean weight by type
The ocean cannot be weighed directly, so its mass is calculated from its volume and seawater density. Holding about 97 percent of Earth's water, it dominates the planet's surface water budget.
| Ocean basin (example) | Relative share of ocean water |
|---|---|
| Pacific Ocean | largest, about half of all ocean water |
| Atlantic Ocean | second largest share |
| Indian Ocean | a substantial portion |
| Southern and Arctic Oceans | smaller shares |
What affects ocean weight
- Total volume. The combined volume of all ocean basins drives the mass.
- Seawater density. Salt water averages about 1,025 kg per cubic meter.
- Salinity. Saltier water is slightly denser and heavier per volume.
- Temperature. Colder water is denser, affecting the average slightly.
- Average depth. The ocean's mean depth of about 3,700 meters sets its huge volume.
- Measurement method. Volume estimates from seafloor mapping feed the calculation.
How ocean weight compares
The ocean weighs roughly 270 times more than all of Earth's atmosphere combined, and it makes up the overwhelming majority of the planet's surface water.
Frequently asked questions
How is the ocean's weight calculated?
Scientists estimate the total ocean volume from seafloor maps and multiply it by the average density of seawater, around 1,025 kilograms per cubic meter.
How much of Earth's water is in the ocean?
About 97 percent of all the planet's water is held in the ocean, leaving only a small fraction as freshwater in ice, rivers, lakes, and the air.
Is the ocean heavier than the atmosphere?
Yes, by a huge margin. The ocean weighs roughly 270 times more than the entire atmosphere, since water is far denser than air.
