How much water is in the Earth’s oceans? 

Oceans contain about 97.2 percent of the total water on the planet. The rest is held in the ice caps, glaciers, the atmosphere (as clouds, snow, and rain), seas, rivers, and lakes.
Another way of looking at the Earth’s ocean water is by volume. Combining all the oceans and seas in the world, the total estimated volume of water on Earth is about 330 million cubic miles (1,400 millon cubic kilometers), but this number can fluctuate with the growing or melting of polar and glacial ice. It is also interesting to note that the Earth’s oceans are estimated to weigh about 1.45 x 10¹⁸ tons, representing a mere 0.022 percent of the Earth’s total planetary weight.