Like solids and gases, liquid capacity can easily be determined using a unit of measurement known as a gallon. *Weight of a gallon of water* measures one unit of fluid capacity in both US customary units and the British imperial system. There are three different gallon sizes used today, namely the imperial gallons used in the UK, Canada and some Caribbean countries, the US gallons used mainly in the US and some Latin American countries, and the US dry gallons are the least used of the three. Three measures of measurement are significantly different from the imperial gallons defined as 4,546 liters, US gallons as 3,785 liters, while dry gallons of US are defined as 4,405 liters.

**Gallons of water**

How many gallons of water is heavy? This is one question that is widely avoided or answered inaccurately by many people. Some people estimate the answer to this question between 5 and 15 pounds. Some people who try to be smart think of it as a complicated question without definite answers. Others will go as far as asking for the temperature of the water. Initially, the weight of water is defined as 1 kg / liter. However, the definition is discarded because the density of water is affected by changes in temperature and atmospheric pressure. The answer is simple; one gallon of water weighs around 8.3 kilograms. The imperial gall of water is defined as 10.02 pounds at its maximum density while the weight of US gallons of dry water is defined as 9.71 pounds. However, the answer comes with a warning. Flat gallons of water fluctuate with temperature.**Effect of Water Temperature on Weight**

Temperature is one way to measure the amount of energy in water. Higher temperatures mean higher energy and vice versa. Higher water energy causes water molecules to vibrate, pushing their neighbors aside. Thus, the density of water decreases with increasing water energy. Because a gallon is the amount of space specified, the number of water molecules in that space will fluctuate with a changing energy level. So, one gallon of warm water weighs a little less than a gallon of cold water with a difference depending on the temperature in question. For example, at 500 Fahrenheit, one gallon of water will weigh around 8.3 pounds while at 2000 Fahrenheit one gallon of the same water will weigh 8.03 kilograms. However, the water value remains the same despite temperature changes because the temperature does not affect the composition of the water.**Atmospheric Pressure and Gravity**

Atmospheric pressure and gravity also affect the weight of a gallon of water or other liquids. *Weight of a gallon of water* will be lighter on the moon compared to Earth but will be heavier on Jupiter than Earth. The difference in weight is associated with the gravitational pull experienced by the object. The earth has a higher gravitational pull compared to the moon, making one gallon of water weigh more on Earth than on the moon. However, just like temperature, the value of water does not change with changes in gravitational pull.