# How Much Does a Gallon of Water Weigh

Gallon is the most commonly used weighing measure. Unfortunately, since it isn't the only unit, you need to know how to convert it into other measures. This is a mensuration guide for a gallon.

ScienceStruck Staff

Last Updated: Sep 6, 2018

*liters*. Here, we deal with the US liquid

*gallon*. To summarize, a gallon of water weighs

**3785.41178 gm.**

Different Gallon Units

For uniformity of usage, all the standard units of measurement are defined by national or international organizations, to eliminate confusion. Of the three definitions of gallon, the one that is most relevant to this discussion is the

*US liquid gallon*.**One US liquid gallon is defined to be 231 cubic inches, which is 3.785411784 liters.**Since 1 liter is 1000 cubic centimeters, a US liquid gallon is 3785.411784 cc. This is equal to 0.133680555 cubic feet. From the knowledge of the density and volume of a liquid, its mass can be calculated. The relation that you need to use is '

*Density = Mass / Volume*'.

Weight in Grams

A gallon of any liquid is exactly 3785.411784 cc. Water's density in a normal temperature range is approximately 1 gm/cc. Therefore, the weight of one gallon of water is simply (3785.411784 cc) x 1gm/cc =

**. That is, it weighs about***3785.41178 gm**3.78541178 kilograms.*Weight in Pounds

One kilogram equals 2.20462262 pounds and one gallon of water is 3.78541178 kg. Therefore, one gallon weighs (3.78541178 x 2.20462262) lbs, which is equal to

**.***8.3454 lb*Weight in Ounces

You might need to know the exact weight of water in ounces. One gallon weighs about

**.***133.526471 Oz*How Much Does a Gallon of Salt Water Weigh?

The weight of a gallon of salt water will vary according to the amount of salt dissolved. The total mass is the mass of water, plus the mass of salt dissolved in it. So salt density and the nature of the dissolved salt needs to be known to know the weight of salt water. It is best to weigh the salt using a standard digital balance, to get an accurate value.