Interesting fact: The ocean holds about 97 percent of Earth's water, so its total weight dominates the planet's surface water budget.
The answer: Earth's ocean weighs about 1.4 sextillion kilograms, or roughly 1.4 x 10^21 kilograms. That estimate comes from the total ocean volume multiplied by the average density of seawater.
The ocean cannot be weighed directly, so scientists calculate its mass from mapped volume and salinity-adjusted density. The result matters for sea-level science, climate modeling, tides, and understanding how heat and carbon are stored on Earth. Even tiny percentage changes in ocean mass or distribution can have huge consequences at planetary scale.
