Gallons to Ounces Converter

US Gallons
UK Gallons
US Ounces
UK Ounces
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Using the Gallons to Ounces Converter

This converter allows you to find equivalent values between the imperial (also referred to as UK) and US Gallons and ounces.

For clarification, an ounce is usually a unit of mass, but in this article, when referring to ounces, we are referring to fluid ounces, a unit of volume.

This converter converts ounces to Gallons between the US and the UK versions exclusively. This means that by selecting the UK Gallon as an input value, you will receive your result as a UK ounce and vice versa. The same applies to choosing a US unit. If your input is the US ounce, your output is the US Gallon and vice versa.

At the top of the converter, choose from the 4 options (Gallons or ounces, UK or US) as your input.

Type in your desired value to convert as a decimal number, or select out of some common options next to the input section.

When everything is set to your liking, choose the number of decimal places you want your result to be rounded toward and click on CONVERT.

Your result will appear as the counterpart unit within the same system, rounded to the desired number of decimal places.

For copying, click on the COPY button next to your result.

Converting Gallons and Ounces Manually

The conversions between these units are determined by the conversion rates between them. In the two following sections, we will talk about conversions between Gallons and ounces in both the US and the imperial (UK) systems.

Converting US Gallons and Ounces Manually

The rates between the US ounces and Gallons are as follows:

  • 1 US Gallon is equal to 128 US fluid ounces
  • 1 US fluid ounce is equal to 0.008 Gallons, rounded to three decimal places.

This allows us to create 2 formulae:

US ~fluid ~ounces = US ~gallons * 128
US ~gallons = ~US ~fluid ~ounces * 0.008

The best way to use the formulae is to choose the one where the subject of the formula is your output value. The two examples below will demonstrate this.

EXAMPLE 1: Convert 2.5 US Gallons into US fluid ounces.

After choosing the first formula, as it has US fluid ounces as the subject, we perform the following calculations.

US ~fluid ~ounces \\= US ~gallons * 128 \\= 2.5 * 128 \\= 320 ~US ~fluid ~ounces.

EXAMPLE 2: Convert 1,000 US fluid ounces into US Gallons.

The second formula is suitable for solving this problem. We substitute 1,000 for the US fluid ounces and solve as follows.

US ~gallons \\= US ~fluid ~ounces * 0.008 \\= 1,000 * 0.008 \\= 8 ~US ~gallons.

Converting UK Gallons and Ounces

Similarly, as in the case of the US units, there are set relationships between the two units.

  • 1 UK Gallon is equivalent to 160 UK fluid ounces.
  • 1 UK fluid ounce is equivalent to 0.006 Gallons, rounded to 3 decimal places.

The following formulae are created out of these conversion rates.

UK ~fluid ~ounces \\= UK ~gallons * 160
UK ~gallons\\ = UK ~fluid ~ounces * 0.006

These two examples will shed some light on how these formulae can be applied in practice for manual conversions.

EXAMPLE 1: Convert 3 UK Gallons into UK fluid ounces.

We will use the first formula and substitute 3 for UK Gallons.

UK ~fluid ~ounces \\= UK ~gallons * 160 \\= 3 * 160 \\= 480 ~UK ~fluid ~ounces.

EXAMPLE 2: Convert 1,450 UK fluid ounces into UK Gallons.

The second formula is the most suitable one for solving this problem.

UK ~gallons \\= UK ~fluid ~ounces * 0.006 \\= 1,450 * 0.006 \\= 8.7 UK ~gallons.

Differences Between UK and US Units of Volume

The US and the UK both have a shared history rooted in the British Empire, which once had a standardized system of units of measurement that was used throughout its territories. However, after the US declared its independence from Britain, it started to develop its own system of measurements, leading to differences in definitions for units such as Gallons and fluid ounces.

Meanwhile, Britain continued to evolve its system of measurements through various influences, including metrication (an influence coming from the rest of Europe, especially France).

The result is that while both countries use similar names for units of volume, the actual values for these units are different. This difference in units can sometimes cause confusion, especially when traveling or working with international partners, and highlights the importance of understanding the specific units being used and how they are defined.

Everyday Items In Different Units

The table below will demonstrate 3 different examples of volumes of familiar objects. This can help gain some perspective on approximation when using UK and US units.

ITEMUK GALLONUS GALLONUK FL. OUNCEUS FL. OUNCE
3 liters of water (the recommended daily amount for an adult)0.660.8105.5102.4
A small can of soda.0.0730.08711.711.1
Average school backpack5.76.9912883