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How Many Ounces In A Gallon (Oz to Gal Conversion + Chart!)

How many ounces are in a gallon?💧 Look no further because we have the answer in this handy guide for US, Imperial (UK), and Metric conversions, along with charts, and more for use in the kitchen and beyond!

how many ounces in a gallon intro graphic.

Have you ever needed to know how to convert between ounces and gallons? Maybe you’ve found yourself in a pinch while cooking or doing household tasks that require precise liquid measurements.

Together we’ll explore the ins and outs of this often-asked question. With handy charts, helpful lists, and FAQs, you’ll become a measurement master in no time.🏅

So grab your measuring cups, and let’s dive into the universe of ounces and gallons!

And for those who just want to know, how many ounces are in a gallon? There are 128 fl oz in 1 US gallon. 🙌

Systems of Measurement

There are three major units of measurement systems: US Customary, Imperial, and Metric. Each system has its own units for measuring volume and mass.

  • US Customary System: Primarily used in the United States, this system has separate units for liquid and dry measurements. Liquid units include gallons, quarts, pints, cups, and fluid ounces, while dry measurements involve units such as bushels, pecks, cups, tablespoons, and teaspoons. Pounds and ounces are used for measuring mass.
  • Imperial System: Common in the UK, Canada, and Commonwealth countries, the Imperial system also uses different units for wet (liquid) and dry measurements. Liquid units consist of gallons, quarts, pints, gills, and fluid ounces, while dry measurements use units like pounds, ounces, stones, quarters, hundredweights, and tons.
  • Metric System: The Metric System, or the International System of Units (SI), is globally adopted and doesn’t use ounces or gallons. Instead, it measures volume in liters and mass in grams, kilograms, and milligrams.

What is a Gallon?

A gallon, abbreviated as “gal,” is a unit of measurement for volume in both the Imperial and US customary systems. It’s mainly used for larger quantities of liquids like fuel, milk, and water. Here you can see the similarities and differences between the two measurement systems.

  • The US liquid gallon equals 4 quarts, 8 pints, 16 cups, 128 fluid ounces, or 3.785 liters.
  • The Imperial (UK) gallon equals 4 quarts, 8 pints, 16 cups, 160 imperial fluid ounces, or 4.546 liters.

What is a Fluid Ounce?

A fluid ounce is a unit of volume used to measure liquids, often abbreviated as “fl oz” or “oz. fl.”. There are two variations: the US fluid ounce and the Imperial (UK) fluid ounce, with slightly different volumes.

  • The US fluid ounce is equal to 1/128 of a US gallon, 1/32 of a quart, or approximately 29.5735 milliliters.
  • The Imperial (UK) fluid ounce is equivalent to 1/160 of an imperial gallon, 1/40 of an imperial quart, or about 28.4131 milliliters.

Both types are commonly used for beverages, liquid medications, and recipes. It’s important to note which system is being used for accurate measurements and conversions.

Wet vs. Dry Gallons

Wet and dry gallons both help us measure space or volume, but they’re used for different things and have slightly different sizes.

  • Wet Gallon: A wet gallon, also called a fluid gallon, measures the space that liquids like water, milk, and gas take up. The US gallon is equal to 128 fluid ounces or 3.785 liters. The Imperial (UK) gallon is bigger and equals to 160 fluid ounces or 4.546 liters.
  • Dry Gallon: A dry gallon measures the space that dry goods, like grains or fruits, take up. It’s not used as much as the fluid gallon. The US dry gallon is about 268.8 cubic inches or 4.405 liters. The Imperial dry gallon is 277.4 cubic inches or 4.543 liters.

While both types of gallons measure volume, they should not be used interchangeably due to their different sizes and intended applications.

Wet vs. Dry Ounces

Wet ounces, or fluid ounces (fl oz), are a unit of volume used for measuring liquids, such as milk, water, or juices. While dry ounces (oz) (aka, avoirdupois ounce) are a unit of weight used for measuring solid substances like flour, sugar, or spices.

It’s essential to differentiate between wet and dry ounces to ensure accurate measurements, as they measure different properties: volume for wet ounces and weight for dry ounces.

This post focuses on fluid ounces (fl oz), and we’ll cover dry ounces in another post!

What is the Difference Between Ounces and Gallons?

Ounces and gallons are both important measurements, but they serve different purposes. Ounces are versatile, measuring both weight and smaller liquid volumes, while gallons focus on larger liquid volumes. Together, they provide ways of measuring units that make everyday life easier and more efficient.

how many ounces in a gallon graphic showing various measurement conversions.

How Many Ounces Are in a Gallon?

Now to answer the big question! Drum roll, please… 🥁

There are 128 fluid ounces in 1 US gallon. In the US Customary System, this conversion can also be expressed as 128 fl oz = 1 (US) gal. While in the Imperial System, there are 160 (UK) fluid ounces in 1 Imperial (UK) gallon. The Imperial conversion can be expressed as 160 fl oz = 1 (UK) gal.

As you can see, the US and Imperial gallons are not the same sizes, so it’s important to use the right system for your specific needs.

How To Convert Fluid Ounces to Gallons (➗)

When converting ounces to gallons, the formulas for both the US and UK systems are simple. Here are the mathematical formulas for each system:

US Customary System

To convert US fluid ounces (fl oz) to US gallons (gal), use the following formula:

US Gallons = US Fluid Ounces ÷ 128

In the US Customary system, 1 US gallon (gal) is equal to 128 US fluid ounces (fl oz). So, to convert any number of US fluid ounces to US gallons, simply divide the number of fluid ounces by 128.

Imperial (UK) System

To convert Imperial fluid ounces (UK fl oz) to Imperial gallons (UK gal), use this formula:

Imperial Gallons = Imperial Fluid Ounces ÷ 160

In the Imperial system, 1 Imperial gallon (UK gal) is equal to 160 Imperial fluid ounces (UK fl oz). To convert any number of Imperial fluid ounces to Imperial gallons, divide the number of fluid ounces by 160.

Here’s a table showing fluid ounces (fl oz) converted to US gallons (gal) and Imperial gallons with the US/UK gallons rounded to 4 decimal places.

Fluid OuncesUS GallonsImperial (UK) Gallons
1 fl oz0.0078 gal0.0061 gal
2 fl oz0.0156 gal0.0122 gal
3 fl oz0.0234 gal0.0183 gal
4 fl oz0.0313 gal0.0244 gal
5 fl oz0.0391 gal0.0305 gal
6 fl oz0.0469 gal0.0366 gal
7 fl oz0.0547 gal0.0427 gal
8 fl oz0.0625 gal0.0488 gal
9 fl oz0.0703 gal0.0549 gal
10 fl oz0.0781 gal0.0610 gal
20 fl oz0.1563 gal0.1220 gal
30 fl oz0.2344 gal0.1830 gal
40 fl oz0.3125 gal0.2440 gal
50 fl oz0.3906 gal0.3050 gal
60 fl oz0.4688 gal0.3660 gal
70 fl oz0.5469 gal0.4270 gal
80 fl oz0.6250 gal0.4880 gal
90 fl oz0.7031 gal0.5490 gal
100 fl oz0.7813 gal0.6100 gal

How to Convert Gallons to US/Imperial Fluid Ounces (✖️)

To convert gallons to US and UK fluid ounces, you can follow these simple mathematical formulas:

  • US fluid ounces (US fl oz) = Number of gallons × 128
  • UK (Imperial) fluid ounces (UK fl oz) = Number of gallons × 160

For example, if you want to convert 2 gallons to fluid ounces:

  • 2 gallons to US fluid ounces: US fl oz = 2 × 128 = 256 US fl oz
  • 2 gallons to UK (Imperial) fluid ounces: UK fl oz = 2 × 160 = 320 UK fl oz

Here is a handy chart for converting gallons to US and Imperial fluid ounces.

GallonsUS Fluid OuncesImperial (UK) Fluid Ounces
1/4 gal (0.25)32 fl oz40 fl oz
1/2 gal (0.5)64 fl oz80 fl oz
3/4 gal (0.75)96 fl oz120 fl oz
1 gal128 fl oz160 fl oz
2 gal256 fl oz320 fl oz
3 gal384 fl oz480 fl oz
4 gal512 fl oz640 fl oz
5 gal640 fl oz800 fl oz
6 gal768 fl oz960 fl oz
7 gal896 fl oz1120 fl oz
8 gal1024 fl oz1280 fl oz
9 gal 1152 fl oz1440 fl oz
10 gal1280 fl oz1600 fl oz

How To Convert Gallons and Fluid Ounces to Metric Units (✖️)

To convert gallons and liquid ounces to metric units, use these easy rules:

  • US fluid ounce to milliliters: 1 US fl oz = 29.5735 mL
  • UK fluid ounce to milliliters: 1 UK fl oz = 28.4131 mL
  • US gallon to liters: 1 US gal = 3.78541 L
  • UK gallon to liters: 1 UK gal = 4.54609 L

To convert a value, multiply the number of liquid ounces or gallons by the right rule. For example:

To convert 5 US gallons to liters: 5 US gal × 3.78541 L/US gal = 18.92705 L

To convert 10 UK fluid ounces to milliliters: 10 UK fl oz × 28.4131 mL/UK fl oz = 284.131 mL

Make sure to use the right rule for the specific system (US or UK) you’re converting. You can also use an online conversion tool to make the conversion super easy. 😊

Here is a useful table expressing conversions for gallons, liters, quarts, pints, cups, US fl oz, and UK fl oz.

US GallonLitersQuartsPintsCupsUS fl ozUK fl oz
1/128 gal0.0296 L0.0313 qt0.0625 pt0.125 c1 fl oz0.9608 fl oz
1/64 gal0.0591 L0.0625 qt0.125 pt0.25 c2 fl oz1.9216 fl oz
1/32 gal0.1183 L0.125 qt 0.25 pt0.5 c4 fl oz3.8432 fl oz
1/16 gal0.2366 L0.25 qt0.5 pt1 c8 fl oz7.6864 fl oz
1/8 gal0.4732 L0.5 qt1 pt2 c16 fl oz15.3728 fl oz
1/4 gal0.9464 L1 qt2 pt4 c32 fl oz30.7456 fl oz
1/2 gal1.8927 L2 qt4 pt8 c64 fl oz61.4912 fl oz
1 gal3.7854 L4 qt8 pt16 c128 fl oz122.9824 fl oz
2 gal7.5708 L8 qt16 pt32 c256 fl oz245.9648 fl oz
3 gal11.3562 L12 qt24 pt48 c384 fl oz368.9472 fl oz
4 gal15.1416 L16 qt32 pt64 c512 fl oz491.9296 fl oz
5 gal18.927 L20 qt40 pt80 c640 fl oz614.912 fl oz
6 gal22.7124 L24 qt48 pt96 c768 fl oz737.8944 fl oz
7 gal26.4978 L28 qt56 pt112 c896 fl oz860.8768 fl oz
8 gal30.2832 L32 qt64 pt128 c1024 fl oz983.8592 fl oz
9 gal34.0686 L36 qt72 pt144 c1152 fl oz1106.8416 fl oz
10 gal 37.854 L40 qt80 pt160 c1280 fl oz1229.824 fl oz

📌 Conversion Chart (US Fluid Ounces, Gallons, Quarts, and Cups)

Pin this conversion chart for later! 📌

US gallon conversion chart.

Should You Drink a Gallon of Water a Day?🚰

The appropriate amount of daily water intake can vary depending on factors such as age, sex, weight, activity level, and climate. While staying hydrated is important, drinking a gallon (128 fluid ounces) of water a day may not be necessary for everyone.

General guidelines from the National Academies of Sciences, Engineering, and Medicine recommend a daily water intake of about:

125 fluid ounces (3.7 liters) for men – about 13 cups
91 fluid ounces (2.7 liters
) for women – about 9 cups

These recommendations include water from all sources, such as beverages and food. However, individual needs can vary, and it’s best to listen to your body’s signals of thirst.


How many ounces in a gallon of milk?
A gallon of milk contains 128 fluid ounces. This is true for all types of liquid gallons in the US customary system, not just milk.

How many ounces in a gallon of ice cream?
There are 128 fluid ounces in a gallon of ice cream, just like with liquid measurements. However, ice cream is denser and contains air, so a gallon of ice cream will weigh less than a gallon of liquid like milk or water.

How many ounces are in a gallon Ziploc bag?
A gallon-size Ziploc bag is designed to hold approximately 1 US liquid gallon. So, it can hold around 128 US fluid ounces.

How many 16 oz bottles of water does it take to equal a gallon? 
It takes 8 bottles of 16 oz water to equal a gallon. This conversion is true since there are 128 fl oz in a gallon. We then divide 128 by 16, which equals 8. Therefore you need 8 – 16 oz bottles of water to equal 1 gallon.

How many fluid ounces are in a 1/2 gallon?
There are 64 US fluid ounces in a US liquid 1/2 gallon (0.5 gallons), and there are 80 Imperial (UK) fluid ounces in an Imperial 1/2 gallon.

How many ounces in 2 gallons?
In the US Customary System, there are 256 fluid ounces in 2 gallons. This conversion is true since there are 128 fl oz in a gal. We can then multiply 128 x 2 gal, which equals 256 fl oz in 2 gal.

How many ounces in 3 gallons?
In the US Customary System, there are 384 fluid ounces in 3 gallons. This conversion is true since 1 gal = 128 fl oz. We then multiply 128 x 3 gal, which equals 384 fl oz in 3 gal.

How many ounces in 4 gallons?
Using the US Customary System, there are 512 fluid ounces in 4 gallons. This conversion is true since there are 128 fl oz in 1 gal. We can then multiply 128 x 4, which equals 512 fl oz in 4 gal.

Is 64 oz the same as 1 gallon?
64 oz is equal to 1/2 gallon. In the US Customary System, 1 gallon equals 128 ounces. Since 64 oz is half of 128 oz, 64 ounces is equal to half (1/2) a gallon (0.5 gallons).

How many gallons are in 32 ounces?
There is a quarter (0.25) of a gallon in 32 ounces.

How many ounces are in a gallon in Canada?
In Canada, the metric system is used, so gallons aren’t a common unit of measurement. Instead, liters are used. If you need to convert between US/Imperial gallons and liters:
1 US liquid gallon = 3.785 liters.
1 Imperial gallon = 4.546 liters.

How many fluid ounces are in a gallon of water?
There are 128 US fluid ounces in a US liquid gallon of water. And there are 160 imperial fluid ounces in an imperial gallon of water.

Food For Thought

Understanding how to convert between gallons (gal) and ounces (oz) can be helpful. Remember to always double-check which system you are using, as the US Customary System and the Imperial System have different conversion factors. Bookmark this guide, and you’ll never be confused about gallons and ounces again!

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