1 US gallon is essentially the same as 128 US fluid ounces

Following the metric system, a gallon of water is measured to be the same as 160 fluid ounces.

Also, how many ounces can we count in a half-gallon? The answer is 64 ounces which makes the whole gallon 128 ounces.

The gallon is described as the unit of quantity that is estimated in imperial units and USA customary units. There are currently three different versions that are presently useful:

First, we have the imperial gallon which is described as 4.54609 liters that were utilized in different countries like the UK, Canada, and some of the Caribbean nations.

The next on the line is the US gallon which is described as 231 cubic inches or 3.785,411,784 liters which is now in use in some places like the US, some Latin American countries, and Caribbean nations.

Lastly, we have the US dry gallon which is described as 1/8 US bushel or 4.404,883,770,86 liters. In a gallon, you could measure out four quarts or even, eight pints inside that gallon.

What we are saying in essence is that a gallon is equal to four quarts and also equal to eight pints.

Although, these are different volumes in different units.

The IEEE basic symbol for the US and Imperial gallon is a gal, which is also used as a unit for acceleration in CGS.


Right now we only work with one definition of a gallon in the imperial system and two in the US customary system which is liquid and dry.

There was a time when we had several definitions with definitions to back them up alongside. Let’s describe the different gallons

English System Gallons

Before the last century, there were different systems used for measuring liquid in the United Kingdom.




Winchester or corn gallon

1697  will III c22

272in^3, 157imp, fl oz. 4460 mL

Henry VII Winchester


150.80 imp fl oz. 4398 mL

Elizabeth I corn gallon


155.70 imp fl oz. 4424 mL

William III corn gallon


156.90 imp fl oz. 4458 mL

Old English Ale gallon or the Elizabethan Ale gallon

1700 will III c15

163 imp fl oz. 4620mL

Old English wine gallon

1706 Anne c27

231in^3, 133imp fl, oz. 3790mL

Irish gallon


217in^3 125imp fl oz. 3560mL

Imperial Gallon

The imperial gallon is best described in figures, and so it is described as 4.54609dm^3 which is utilized in most commonwealth countries before 1976 and mainly pertained to the volume of 10 pounds of water at 62 degrees Fahrenheit.

It is known that a gallon has four quarts and the imperial pint is also described in liters as 0.56826125 literal where there are 20 imperial fluid ounces in an imperial pint.

US Liquid Gallon

The US Liquid gallon which is also known as just a gallon is defined according to the system as 231 cubic inches which is also equal to 3.785411784 liters.

A gallon of water in the US weighs almost 8.34 pounds which is the same as 3.78 kilograms at 62°F and that makes the imperial gallon heavier than it by 16.6%.

A gallon as we have said repeatedly has four quarts, a quart then has two pints, and 16 there are 16 US fluid ounces in a US pint, which means that a US fluid ounce is directly equal to 1/28 US gallon.

The reason why we specify the temperature at which the exact volume we are given out was taken is that contraction and expansion occur with temperature and for the purpose of trade, it is best to do this.

What the previous paragraph is saying is that temperature affects the gallon size and so it can take more or less fluid with time and so it is best to tell the exact temperature at which the gallon is kept when the volume was measured.

An instance is the volume of petroleum-based products and also alcoholic-based beverages which are both put at 60°F in standard regulations.

  • US Dry Gallon

The relationship between a pint and a gallon is the exact relationship that a dry measure has with a Winchester bushel of about 2150.42 cubic inches.

This measurement now makes it the same as the normal 268.8025 cubic inches which are now 4.404,883,770,86 L.

The US dry gallon is not allowed in commerce and is also not scheduled in the important law that moves with the dry pint and the bushel.

The Imperial System Of The US And UK

The UK imperial and the US system are just different kinds of imperial systems.

Both were known to be the most popular because of their improvement in technology and increment in the economy and population.

The metric policy arrived late into enforcement and presently, most people utilize the world metric system.

Because the world has become a marketplace for everyone, for other people to easily get access they utilize the basic units so they don’t get misunderstood and obstacles in their business.

Still, we have noticed that the US and British had utilized their system as it is now among the rules which makes it difficult for the people there to switch to something else.

It is also not simple to move into the new metric system that came very late into the world practice.


1 US fl gallon equals 3.785 liters

1 liter equals 33.814 US fl oz.

1 fl gal 3.785 multiplied by 33.814 equals 128 oz.


1 imperial fl gallon equals 4.54609 liters

1 liter equals 35.1951 UK fl o

1 fluid gallon equals 4.54609 multiplied by 35.1951 equals 160 ounces.

Converting gallons To Ounces

Converting ounce to gallon used to be something everyone wanted to know about, but when the standard units started, it ended up not being a big deal.

There are two variations of measurement policies that are occurring I’m in today’s world.

We have the imperial British measurement system and the USA measurement system.

Although a different one was mentioned and explained previously in this article.

How It Is Used Worldwide

In this section, we will be explaining how the imperial and US liquid gallon is used worldwide.

Imperial Gallon

As it is right now, the imperial gallon is in use continually as the basic petrol unit in different(four) British overseas territories like Anguilla, the British virgin islands, the Cayman Islands, and Montserrat.

Also, this is the basic petrol unit in six different countries, such as Antigua and Barbuda, Dominica, Grenada, Saint Christopher and Nevis, Saint Lucia, and Saint Vincent the Grenadines.

Something is common among the countries that use this imperial gallon as their petrol unit, they make use of miles per hour when calculating speed and they all maintain the left lane when driving.

The United Arab Emirates once used the imperial gallon system for petrol but later stopped along the line in 2010 when they changed to using liter.

Guyana also did the same thing that the United Arab Emirates did, although not at the same time because they switched in 2013.

Some countries have also done this same thing, for instance, we have countries like Burma which switched over to the liter system in 2014.

Also, we have a country that did something like this and moved to a liters system, talking about Antigua and Barbuda.

The gallon system was taken away from the list formally of the described major units of measure written in the directive of the EU.

This was something about the 80/181/EEC for trading and official uses with the outcomes from 31 December 1994.

While under this system, the gallon could also be in use but mostly as last resort but not as a major.

One of the outcomes of this system was that the United Kingdom changed its legislation to change gallon with the liter as a major unit to measure while trading.

Although, in the United Kingdom and Ireland, several barrels and huge packs of beer, oil, and some other fluids are mostly measured in Imperial gallons.

Ireland as a country has also passed the law while responding to the rule of the EU and this took place on the 31st of December 1993.

Although the gallon has been seen to be a major unit for trading, it is still allowed for use in the UK and Ireland only as a secondary unit, again it cannot be used as the major unit.

In the UK, the speed is measured mainly as miles per imperial gallon which is now the major economy unit.

While in Canada, miles per imperial gallon is used as a supplementary unit when used in the official documentation.

In the United Arab Emirates, water-chiller bottles are being used in different multiples of the imperial gallon.

US Liquid Gallon

Apart from the United States of America, petrol is given by the US gallon in places like Belize, Colombia, Dominican Republic, Ecuador, Guatemala, Haiti, Honduras, Liberia, Nicaragua, And Peru.

Also, petrol can be sold by the US gallon in places like the Marshall Islands, Federal States of Micronesia, and Palau. These three places are associated with the United States Of America as we should know.

Not minding what it is as a US territory and nothing like American Samoa the Northern Mariana Islands, Guam, and the US Virgin Islands, Puerto Rico had stopped selling its petrol using the US petrol gallon since 1980.

Panama also has stopped selling petrol with US gallons since 2013 and adopted the use of liters.

El Salvador is another country that stopped the use of imperial gallons while selling petrol and started using liters ever since June 2021.

In places like the Turks and Caicos Islands, they use both measurement systems, the US gallon and the Imperial gallon are being used there.

This is done because of the increment of taxes which was introduced as something else by levying similar tax duties on the US gallons as it had been levied before on the Imperial gallon.

Even the Bahamas are currently using both systems, that is, the US gallon and the Imperial gallon.

How Is It Related To Other Units

A similarity between US liquid and Imperia gallon is the fact that both of them are distinguished into four parts.

Each of the four parts is divided into two parts called pints. The four parts themselves are called quarts.

The pints are then divided into two cups, while the cups are then divided into two gills.

Therefore, the salons, that is the US gallon and imperial gallon are both divided into four quarts, eight pints, sixteen cups, and thirty-two gills.

The imperial gill is now split into five fluid ounces, while the full itself is split into four fluid ounces, what does this mean? What e are saying here is that:

An imperial fluid ounce is 1/20, of an imperial pint, or you could take it as 1/160 of an imperial gallon.

A US fluid’s ounce is measured as 1/16 of a US pint, or 1/128 of a US gallon.

What It implies here is that by the measurement of the imperial gallon, quarts, pints, cups, and gills are larger than the US gallons by approximately 20%.

This implies that they are not interchangeable. The imperial fluid ounce is just 4% smaller than the US fluid ounce, this means that they are often used interchangeably.

Normally, according to what history has told us, the normal size of a bottle of liquor in the USA used to be the fifth of a US gallon, you understand when something is the fifth, it means that it is one-fifth of the other item.

While the sales of spirits which are alcohol in the US were changed to a metric measurement system in 1976.

A bottle of 750mL is still measured sometimes as a fifth.

Also, it is added that one-fifth of a US gallon is approximately one-sixth of the Imperial gallon.


The term gallon is quite confusing as to where it came from, many people say it has a slight resemblance to the old Northern French word ‘galun’.

The word has been in use in so many different languages, for instance, we had it being used in old French as jale, while in old English it was called gullet.

Some people have suggested that the word must have come from the Latin area, the thing is that no one is sure of where it is from so we just keep guessing, and till today no one is sure of where this word has originated from.

The word gallon has been used as the foundation of different systems for measuring wine and beer in the UK.

The different sizes used in these two systems differed so much from each other.

The first one was related to the wine gallon which is equal to the size of the present US gallon.

The second one known as the Ale gallon can also be called the imperial gallon.

After the 18th century, gallons could be defined in three different ways commonly.

First is the corn or Winchester gallon which was measured as about 268.8 cubic inches which is now the same as 4.405 L

The second is the wine gallon or the Queen Anne‘s gallon which was 231 cubic inches and also 3.785 liters.

The last one was the ale gallon known as 282 cubic inches and is equal in liter to 4.622L.

The corn or dry gallon is utilized alongside the dry, quart, and pint in the USA for grain and some other dry products.

It is measured to be one-eight of the Winchester bushel which was defined majorly as the cylindrical measure of about 18 and a half inches in diameter while as deep as 8 inches.

This makes the dry gallon 8 inches multiplied by nine and a quarter inches square multiplied by pi.

After on, the bushel was described as 2150.42 cubic inches to be precise which made its gallon exactly 268.8025in^3.

In the centuries beforehand, there has been a corn gallon that ranged from 271 to 272 cubic inches.

The gallon which can be used to store wine, fluid, or liquid has been the basic US gallon since it was established in the early 19th century.

The wine gallon that some people have related to the volume taken up by eight medieval merchant pounds of wine used to be described as the volume of a cylinder that is about 6 and 7 inches deep when measuring in diameter.

It was later described during the queen’s reign in the year 1706 as 231 cubic inches which was the same definition but with pi included.

Even though the wine gallon has been utilized for years just to bring it in.

In the year 1824, the British brought in a close similar figure to the ale gallon which is now known as the imperial gallon.

With this system, they have successfully removed all other gallons so that this particular gallon could work better for it.

In 1963, the definition was later changed to be the space filled up by 10 pounds of distilled water with a density of 0.998 859 when weighed in the air.

How Many Ounces Of Water Should Be Drank In A Day By A Human Being?

Scientists or health experts have said that it is mandatory that to keep a healthy posture and remain healthy, a person must drink at least 8 standard glasses of water every day which is now followed by what the body requires. In case you don’t know, one glass of water, talking about standard glass, is equal to 8 fl ounces and 160 fl ounces is the same as a gallon when measured.

How Many 16.9 oz. Is Present In A Gallon?

This might seem complicated because of the way the question was displayed. The answer would be gotten once you understand the question. We have 7.57 bottles of the 16.9 US fluid ounce of water which is equal to one US gallon. The measurement system of the US has a massive distinction from the way imperial measurement system and the international metric system too.

A Half Gallon Of Water Can Be Measured To Be How Many Ounces?

So the question here is straightforward and the answer is 64 fl oz. Are present in the half-gallon of water.

How Many Fluid Ounces Do We Have In A Gallon?

As we know already through this article, we have three different kinds of gallons namely; the US customary fluids and dry gallons, the imperial gallons.

Also, there are two kinds of fluid ounces available right now that we know of, there are the US customary fluid ounces and the imperial fluid ounces. Presently big all depends on what kinds of gallons and fluid ounces are being utilized, the answer to this question might then differ.

If you were keen on converting the US fluid gallons to fluid ounces, then the answer to your question would be 128 fluid ounces in a gallon. When the conversion is then taken between the imperial gallons and Imperial ounces, your answer would be 160 imperial fluid ounces.

How Is The Conversion From Gallons To Ounces Done?

There are about 128 ounces found in a gallon when you are trying to convert gallons to ounces, the easiest way is to multiply the value of your given gallon by 128.

This is what we mean when you are good to convert one gallon to an ounce, you multiply by 128 and then you get 128 ounces as your conversion value.

How Many Water Bottles Can Be Measured In A Gallon?

We have one US gallon converted to 128 US fluid ounces. To figure out the number of water bottles in the gallon, you just do what you did before and multiply the number of gallons by 128 and then divide whatever you get by the size of the water bottle measured in fluid ounces. For instance, figuring out the amount of 16.9 oz. Water bottles are present in 3 gallons then you would just have to multiply 3 by 128 and then divide by 16.9 oz.

Categories: General

Nicolas Desjardins

Hello everyone, I am the main writer for SIND Canada. I've been writing articles for more than 12 years and I like sharing my knowledge. I'm currently writing for many websites and newspapers. I always keep myself very informed to give you the best information. All my years as a computer scientist made me become an incredible researcher. You can contact me on our forum or by email at [email protected].