On average, seawater in the world's oceans has a salinity of approximately 3.5%, or 35 parts per thousand<span>. This means that for every 1 litre (1000 mL) of seawater there are </span>35 grams<span> of salts (mostly, but not entirely, sodium chloride) dissolved in it.</span>
About 35 parts per thousand<span>The concentration of salt in seawater (salinity) is about 35 parts per thousand. Stated in another way, about 3.5 percent of the weight of seawater comes from the dissolved salts; in a cubic mile of seawater, the weight of the salt (in the form of sodium chloride) would be about 120 million tons.
