# How Much Does a Gallon of Water Weigh

How much does 5 gallons of water weigh?

5 Gallons (Us fluid) equals to 18.9270589 Litres.

Almost all of the other answers here were correct (with varying degrees of precision) but essentially said that water weighs (for a US gallon) 8.34 pounds so multiply by 5 and your answer is lbs.But as you have probably learned in class, or at least heard somewhere, cold water is more dense than warm water, which is why water coming South from the arctic regions (in general, but especially as result of melting ice) sinks below the warmer water which is flowing toward the North, arriving from Florida on the Gulf Stream current. This effect is important to keep the large general ocean currents flowing, but it also shows that the 8.34 or 8.345 or even the 8.345404 pounds is a standardized quantity at the specific of standard temperature and pressure.

1 gallon of water = 3.78541178 litre | 5 gallon of water = 18.9270589 litre1 litre of water has an index mass of ~1.000 Thus, 1 litre of water = 1.000kg18.9270589 litre of water = 18.9270589 kg

5 gallon of water = 18.9270589 kgOr in pounds, 18.9270589 x 2.20462 = 41.726972592118 pounds.

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How Much Does a Gallon of Water Weigh? Easy Calculation 1

Question: How much does a gallon of water weigh?

Answer: A US gallon of water weighs 8.34 lbs or 3.78 kg at 62 °F (17 °C). An imperial gallon (UK) weighs 10.022 lbs or 4.546 kg, at its most dense temperature, which is 2.20456 lbs / L at 4 °C or 39 °F.

Ballpark Calculation (for all temperatures)

1 gallon is about 3.75 liters
1 liters = 1 kilogram (density of water is 1 kg/liter)
1 kg is about 2.2 lbs
so, 3.75 kg is about 8.25 lbs and 1 gallon is about 8.25 lbs

Three Different Units of Gallon
It makes a difference which unit of gallon you are using. There are two US definitions of gallon. The US liquid gallon (most commonly used) is defined as 231 cubic inches, which is 3.785 liters, and weighs 8.344 lbs at its highest density.

The US dry gallon is defined as 1/8th of a US bushel, which is 268.8025 cubic inches or 4.405 L. The weight of a US dry gallon is 9.711 lbs of water at its highest density.

The UK gallon or imperial gallon originally was defined as 10 lbs of water, but the modern definition is exactly 4.54609 L or 10.02 lbs of water at its maximum density.

Effect of Water Temperature on Weight
Cold water is more dense than ice or than warm water or liquid just above freezing. This is an unusual property of the substance, resulting from hydrogen bonding. So, a gallon of warm water would weigh slightly less than a gallon of cold water. The exact difference would depend on the temperatures in question, but it doesn’t affect the value by much.

Of course, gravity affects weight too, so a gallon of water (or anything else) would weigh more on Jupiter than on Earth, while it would weigh less on the Moon than Earth.

Easy Way To Remember the Weight of Water
While you’ll want to keep the exact volume definitions in mind for scientific calculations, for everyday use you can remember the weight of water using the simple rhyme: A pint’s a pound, the world round.

The saying refers to the rough equivalence between 16 fluid ounces (a pint) and 16 ounces avoirdupois weight. A gallon is 4 quarts or 8 pints, so a gallon weighs approximately 8 lbs.

How Much Does A Gallon Of Water Weigh?

A gallon of water weighs around 8 pounds at its most dense state.

Like solid and gas, the capacity of a liquid can easily be determined using a unit of measurement known as a gallon. A gallon measures a unit capacity of liquid in both the US customary units and British imperial system. There are three different sizes of gallons in use today, namely the imperial gallon used in the UK, Canada, and some Caribbean countries, the US gallon used mainly in the US and some Latin American countries, and the US dry gallon which is the least used of the three. The three sizes of measurements are significantly different with an imperial gallon defined as 4.546 liters, US gallon as 3.785 liters, while US dry gallon is defined as 4.405 liters.

A Gallon of Water
How much does a gallon of water weigh? This is one of the questions that is widely dodged or inaccurately answered by many. Some people have estimated the answer to this question to be between 5 and 15 pounds. Some people trying to be smart have treated it as a tricky question without an exact answer. Other people will go as far as asking the temperature of water. Initially, the weight of water was defined as 1 kg/liter. However, the definition was discarded since the density of water is affected by changes in temperatures and atmospheric pressure. The answer is simple; a gallon of water weighs about 8.3 pounds. The imperial gallon of water is defined as 10.02 pounds at its maximum density while the weight of US dry gallon of water is defined as 9.71 pounds. However, the answer comes with a caveat. The weight per gallon of water fluctuates with temperature.

Effects of Water Temperature on Weight
Temperature is one of the ways to measure the amount of energy in water. A higher temperature means higher energy and vice versa. Higher water energy causes water molecules to vibrate, pushing their neighbors to the side. Thus, the density of water decreases with the increase in energy of water. Since a gallon is a set amount of space, the number of water molecules in that space will fluctuate with the changing energy levels. So, a gallon of warm water weighs slightly less than a gallon of cold water with the difference depending on the temperatures in question. For instance, at 500 Fahrenheit, a gallon of water would weigh approximately 8.3 pounds while at 2000 Fahrenheit a gallon of the same water would weigh 8.03 pounds. However, the value of water remains the same despite the temperature changes since the temperature does not affect the composition of water.

Atmospheric Pressure and Gravity
Atmospheric pressure and gravity also affect the weight of a gallon of water or any other liquid. A gallon of water will weigh less on the moon compared to the Earth but will weigh more on Jupiter compared to the Earth. The difference in weight is attributed to the gravitational pull experienced by objects. The earth has a higher gravitational pull compared to the moon, making a gallon of water to weigh more on Earth than in the moon. However, just like temperature, the value of water does not change with a change in gravitational pull.