How much heavier is salt water than fresh water per gallon?

Seawater has a salinity of about 10,000 to 35,000 ppm. This means that there are about 10,000 to 35,000 parts “salt” to every 1,000,000 parts water. If you think of it like baking, it means that for every 100 cups of apple you add to your apple pie, you add between 1–3.5 cups of flavouring (sugar, cinnamon etc.). read more

It depends on how much salt is in it. Fresh water has a density of about a kilogram per liter, or about 3.78 kg (8.33 pounds) per gallon. Seawater has a density of about 1.03 kg/L, or about 8.57 lb/gallon. read more

Although an entire gallon of water weighs 8 pounds, a single molecule of water weighs 2.992 x 10^-23 grams. An entire mole of water is needed to weigh just 18 grams. Salt water weighs more than fresh water, and the variance depends on how salty the water is. Sea water is very salty. read more