How many Ounces in a Gallon | Oz to Gallon

Last updated: September 14, 2020

Oz to Gallon is a volume conversion unit. The abbreviation oz means Ounce. It broadly uses in the United States and English speaking countries like the UK. The primary use of Ounce is in package foods and Drinks. However, the fluid ounce is more well known and in use. Such as in bars or liquor stores. So, now the question is how many ounces in a gallon?

Oz to Gallons
fl Oz to Gallon

Oz to Gallon Conversion

A gallon is also a unit for fluid volume measurement. The unit Gallon is used in both US customary unit and the Britsh imperial system of measurement. But, it has a difference. This difference is in quantity.

1 fluid ounce equal to 0.0078125 gallons [US]

1 fluid ounce equal to 0.00625 gallons [UK]

Gallons to Fluid ounce

1 US Gallon is equal to 128 ounces.

1 UK Gallon is equal to 160 Ounces (imperial fluid ounces).

Ounces to Gallon

Type a value in the Ounce field to convert the value to Gallons [US]:


Type a value in the Ounce field to convert the value to Gallons [UK]:


However, gallons as a unit of the volume are popular in the US, UK, Canada, and many Caribbean countries. But, after the metric system was accepted as a unit of the SI system, many countries replaced it with litres. At present, Gallon has two definitions. Firstly, according to the British Imperial system and secondly, the US customary system.

In addition, there are two definitions of gallons in the American customary system. One is liquid gallon, likewise the other is a dry gallon.

Imperial system

1 Gallon is equal to 4.54609 Litres [ UK]

US Customary system

1 Gallon is equal to 3.78541 Litres [Liquid Gallon, US]

1 Gallon is equal to 4.40488 Litres [Dry Gallon, US]

Ounces to Litres

Type a value in the Ounce field to convert the value to Litres [US]:


Type a value in the Ounce field to convert the value to Litres [UK]:


Oz to Gallon History and additional information.

The unit ounce is not only for measuring volume but is also a measuring unit of mass and weight. To clarify, Originally an ounce is the unit of mass. The fluid ounce was defined by the volume occupied by a substance, for example, an ounce of water or alcohol. Thus, various ounces were used for centuries. It first came into use in the 13th century for the weight of foods and commodities. Traders made commercial use of this unit. This unit system was called the Avoirdupois system. But in 1824, the British Parliament defined the imperial gallon as the amount of 10 pounds of water at zero degrees Celsius. Thus, a gallon should have 160 ounces. However, the US fluid ounce measure is based on US gallons which are based on a wine gallon of 231 cubic inches and equal to 128 ounces.

In1959, Ounces (oz) became an internationally agreed entity by countries that use the pound as a large-scale unit.

Hence, 1 ounce = 28.4130 ml in the UK but in the US, 1 ounce = 29.5735 ml

For serving nutritional charts on foods, 1 ounce is equivalent to 30 ml, according to the US Food Labeling Regulation.

Conversion Table [Fluid, US]

GallonFl. OunceGallonFl. OunceGallonFl. OunceGallonFl. Ounce


So the conclusion for “how many ounces in a gallon” depends on where you are. If you need more information, comment below. We would love to help you.

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