Since the beginning of humankind, we have had to find a way to express the physical world through numbers. That is so we get a little more insight into the effect certain phenomena can have on us. One way to express the real world with digits is by using volume. The volume shows us how much space something is occupying. For example, the volume of a house is much larger than that of an aquarium. It may seem useless to calculate how much space something occupies if we can see them. But if you look at something on a much larger or smaller scale, things start to get more complicated. With our Gallon Calculator you will be able to easily convert between gallon and different units of volume.

In the following text we will present what is a gallon, basic conversions and how to use our calculator. Moreover we will show a couple of examples of conversion. Meanwhile, you can check our other products in conversion section, or maybe if you are interested in our Octagon or Spherical Coordinates Calculator from math section.

Take a look other related calculators, such as:

What is a gallon?

A gallon is a unit of measure for volume. It might seem odd to someone who uses gallons and liters to use them for the volume of something. That’s because gallons and liters are more often connected with liquids. Officially, the unit for volume is cubic meter, but people often use gallon because it’s more practical.

There are three versions of a gallon: imperial gallon, used in places like the United Kingdom; US gallon, which is used in the US; and US dry gallon. These versions have different sizes, and all are used in appropriate areas. The symbol for gallon is the gal. You probably encountered a gallon if you went to the gas station in the American parts of the world.

Term gallon came from the French language. Historically, there were even more versions of this unit. With our Gallon Calculator, you will easily convert between different units of volume.

Convert liters to gallons – metric units

One US gallon is equal to 3.7854 liters. To convert from liters to US gallons, we should divide the number of liters by 3.7854. One liter is equal to one dm3 of volume, which means we can convert all of this to an SI metric system.  There are other gallon versions, but the most popular is the US gallon. Moreover, one dry US gallon is 4.405 liters.

Convert cubic feet and inches to gallons

One cubic foot is a volume of space inside a cube, one foot long, one foot wide, and one foot high. One foot is equal to 0.3048 meters. That means that one cubic foot is the equivalent of about 0.0283 cubic meters, which means that one cubic foot contains about 28.3168 liters or around 7.48 gallons. One gallon contains 231 cubic inches. To convert cubic feet to gallons, you can multiply the number of square feet by 0.0283 and convert cubic inches to gallons. To do that, you have to divide the number of cubic inches by 231.

Convert quarts to gallons

A quart is a unit of volume equal to a quarter of a gallon, or about one liter. Like with gallon, you have multiple versions of the quart. Those include imperial quart, US liquid quart, US dry quart.

Gallons=Quarts \div4

Convert ounces to gallons

Name “ounce” refers to multiple units – of mass, volume, or weight, but we are just interested in ounces used for volume, sometimes referred to as fluid ounces. A fluid ounce is derived from a gallon, so it isn’t hard to convert between them.

Fluid \; Ounces=Fluid \; Gallons \times128
Fluid\; Gallons=\frac{Fluid\;Ounces}{128}

We can see that one gallon is equal to 128 fluid ounces.

Convert gallons to cups

Cup is a unit of volume, primarily used in cooking. Like the name suggested, this unit comes from a standardized version of an ordinary cup.

Gallon to cup convert
Measuring cup used for cooking

Thus, there are many versions of cup units because many parts of the world have their standards. For example, to convert US gallons to cups, we can apply this formula:


Water – gallons to kilograms and pounds

All of the mentioned units are based on the volume that an appropriate amount of water takes up in space. One liter of pure water weighs exactly 1 kg. So converting from gallons to kilos is the same as converting gallons to liters. To convert from gallons to kilograms, use the formula:


That means that we can now calculate the weight of the water in a fish tank or a pool. To convert gallons to pounds of pure water, apply this formula:


How to calculate gallons in a pool?

Calculating the volume of a pool in gallons is relatively an easy task. It’s similar to calculating the volume of a fishing tank or rectangular box. However, there is no one-dimensional equivalent to a gallon, so we must use cubic meters. That is because the box’s volume is calculated by multiplying its length, width, and height (depth) or by multiplying base area with height, and we can’t express those in gallons. Then, we will convert the volume from cubic meters to gallons. To calculate the volume of the pool in gallons, we can use the formula:

Volume \; in \; Gallons=Length \times Width \times Height (Depth) \times Gallons

Where length, width and height (depths) are in meters, while gallons are in cubic meters.

Volume \; in \; Gallons=Volume\;of\;Pool\times264.172

To calculate volume of pool, tank or any other rectangular box in cubic meters, check our Volume Calculator.

How to use the gallon calculator?

When you open the Gallon Calculator in our app, the app will first present you with two choices: volume converter or water-gallons to weight. If you choose the first one, you can convert between all the different volume units at the same time. If you choose the second one, you will be able to enter the volume of water (by default, the fields are set to US gallon, cubic meter, cubic inch) and convert it to the other two. In this mode, the calculator even has a density field, which means that you can enter the density of water and get the mass of water inside that volume.

Example – gallons to pounds

Let’s convert between gallons and pounds of liquid of a certain density with the following formula:

Weight = Volume \times Density

Where weight is in pounds, volume in gallons and density in pounds per gallon.

Doing it this way will ensure that all the appropriate units will cancel each other out and that we are left with weight in pounds. Or you can do it with our calculator. In the first field, choose the option “Water – gallons to weight .” Then make sure that in the next section, you use appropriate units:

  1. In the first field, make sure to choose US gallon as a unit
  2. Fourth field (density): make sure that the unit is pounds per gallon
  3. In the last field (weight, imperial), choose pounds

Then, enter the volume in the first field and the density of your fluid in the “density” field. Finally, you should see the weight in pounds displayed in the last field.