Have you ever wondered how many ounces are in a gallon? Well, the math is easy but even better, I have done it all for you. This article has all the answers plus several handy conversion charts that are free to print. These guides handle converting fluid oz to a gallon or gallons to ounces so you have everything you need.
Liquid measurements can show up in recipes as pints, gallons, ounces, quarts, & cups. And though you may want to mix a gallon batch of my recipe for Candy Corn Martini for Halloween, you probably only want to drink a few ounces yourself.
Trying to convert one with the other can give you a headache. Doing so between two different measurement systems makes it even more confusing. If you have ever needed to convert US or Imperial ounces to gallons, you likely wished there was a shortcut. Now there is with everything shared here today.
For the sake of this article, we will explore both so you have all you need. Here is what this article will cover and reference.
- US Gallon vs Imperial Gallon
- US Ounce vs Imperial Ounce
- How Many Fluid Ounces in a Gallon
- How to Convert Gallons to Ounces
- Gallons to Ounces Printable Conversion Chart
- How to Convert Ounces to Gallons
- Ounces to Gallons Printable Conversion Chart
- How to Measure Fluids Correctly
- Top-Rated Kitchen Measuring Tools
- More Free Conversion Chart
US Gallon vs Imperial Gallon
What is a gallon? I bet you didn't realize there is more than one way to measure a gallon. Well, there is!
There are two main types of measurements used around the world. Imperial and metric measurements. The United States and two other countries are the only ones still not using the metric system.
But there is a slight difference in what a US gallon weighs versus an Imperial gallon that some countries still go by. The UK and its territories use an Imperial gallon measurement which is different than a US gallon.
The US gallon is smaller than the UK/Imperial Gallon
A gallon in the USA is 20% less than a gallon in England.
- 1 US gallon = 3.785 liters
- 1 UK gallon = 4.546 liters (litres in British Spelling)
The US gallon is based on the volume of a cube with sides measuring 1 inch, consisting of ten such cubes. Its precise value is 231 cubic inches or 3.785 liters.
In contrast, the Imperial gallon was initially determined as the volume of a cylinder with a height and radius of 1 foot each. It is equivalent to approximately 4.55 liters or 4 Imperial quarts.
US Ounce vs Imperial Ounce
What is an ounce? Now you are probably wondering if a US ounce is different than an Imperial ounce. I am glad you are because, yes just like the gallon measurement, the ounces are different too. Stay with me, it will be less confusing as we continue.
Let's continue with what a fluid ounce is. A unit of volume is measured in fluid ounces. (Dry ounces go by weight.) The opposite is true for ounces when you compare US ounces to Imperial ounces and which is more.
The US Ounce is Bigger than the Imperial Ounce
An ounce in the USA is 4.08% larger than an ounce in the UK.
- 1 US liquid oz = 29.5735 mL
- 1 UK liquid oz = 28.4131 mL
An ounce is a unit of weight, while the gallon is a unit of volume. In order to convert between the two, it is necessary to have knowledge of the density. That is why there is all this math.
How Many Fluid Ounces in a Gallon
So now that you understand there are two different ounces and gallons, let's find out how many ounces makeup one gallon.
One US liquid gallon equals 128 US fluid ounces
1 gal = 128 fl. oz. in America
One Imperial liquid gallon equals 160 Imperial fluid ounces
1 gal = 160 fl. oz. in the UK & its territories
How to Convert Gallons to Ounces
Math time for those that want to know how we get to the conversions in the charts. For a test run, let's find out how many ounces are in 3 gallons.
- To convert US gallons to US fluid ounces, multiply the number of gallons by 128, (the conversion factor): gal x 128.
Example: 3 gallons is 3x128 = 384 US oz
- To convert Imperial gallons to Imperial fluid ounces, multiply the number of gallons by 160, (the conversion factor): gal x 160.
Example: 3 gallons is 3x160 = 480 UK/Imperial oz
Now that we have the math that explains how to convert ounces to gallons, let's uncover the answer to how many fluid ounces are in a gallon.
Gallons to Ounces Printable Conversion Chart
Here's an uncomplicated chart for converting liquid measurements from US gallons (gal/gl) to US ounces (oz), which can be used as a quick reference guide. This helpful conversion chart includes fractions and is easy to use.
Print Free Gallons to Ounces Conversion Chart
How to Convert Ounces to Gallons
The opposite math is done when you are converting ounces to gallons. Since ounces are smaller, earlier the math was a multiplication equation. A gallon is larger than an ounce; therefore, we will now divide it to come up with the conversion.
- To convert US fluid ounces to US gallons, divide the number of ounces by 128, (the conversion factor): oz ÷ 128.
Example: 30 oz is 30÷128 =.234375 US gallons
- To convert Imperial ounces to Imperial gallons, divide the number of ounces by 160, (the conversion factor): oz ÷ 160.
Example: 30 oz is 30÷160 = .1875 UK/Imperial gallons
Ounces to Gallons Printable Conversion Chart
Here's an uncomplicated chart for converting liquid measurements from US fluid ounces (oz) to US gallons (gal/gl). It's a great quick reference guide. This conversion chart is easy to use.
Print Free Ounces to Gallon Conversion Chart
Here are answers to some common questions. I hope you find what you need but if not, you are always welcome to send me a comment and I will get back to you.
How many ounces are in a gallon of water?
It is important to drink the right amount of water each day. Making sure you drink enough fluids is key to good health. A gallon is quite a bit to consume but some people that are very active or breastfeeding moms may need to consume that much in a day.
A gallon of water sold in US supermarkets contains 128 US fluid ounces, while a British gallon of water has 160 UK fluid ounces in the UK. So when you think about the saying "drink 8 glasses of water a day"... a typical glass is 8 ounces so that would be 64 oz or one-half gallon of water a day.
How many ounces are in a gallon of milk?
A gallon of milk sold in US supermarkets contains 128 US fluid ounces, while a British gallon of milk has 160 UK fluid ounces in the UK.
How many ounces in half a gallon?
Since one gallon in the US is 128 ounces, half a gallon would be 64 fluid oz. A half gallon in the UK/Imperial measurement would be 80 ounces.
One gallon equals how many ounces?
A single gallon measured in the USA is equal to 128 ounces. One gallon in the UK or its territories use Imperial measurements and it equals 160 ounces.
How many cups are in a gallon?
Each cup is 8 ounces. So you will need to divide 128 by 8 to get the answer. There are 16 cups in a gallon.
If you are drinking water bottles, you can figure out how many gallons there too. You will need 16 8-ounce water bottles to equal a gallon. Or 8 16-oz water bottles.
How to Measure Fluids Correctly
Measurings liquids precisely when cooking or baking is important. First off, make sure you have the right tools, such as a liquid measuring cup, to do so. They make large gallon-sized measuring cups which are ideal for handling a lot of liquid. I have a 3-cup set by Pyrex that has a large 36-ounce size included.
Make sure you are using a clear measuring cup. These are made specifically for measuring liquid ingredients. The glass or plastic materials make it easy to see the lines for accuracy. Plus the handle and spout are best for pouring liquids.
Here are recommendations for products that are needed for this article. Shop this list and buy these customer-favorite items today.These are the best liquid measuring cups for all sizes - gallons, pints, cups, and many ounces.
The Short Order Cook participates in the Amazon Services LLC Associates Program. As an Amazon Associate, I earn from qualifying purchases. If you click on a link and make a purchase, I may earn a small commission on the sale at no additional cost to you. This helps with the costs of running the blog. Thank you!
More Free Conversion Chart
Keep it easy in the kitchen with all these FREE printable guides for measuring in the kitchen. No math is needed, just print, save, & refer to it when needed. Happy Cooking!
Top Tips & Final Notes
Here are my top tips for measuring fluid ounces & gallons.
- Use measuring cups that are specific for fluids. The best products are shared above. They have a see-through design, handle, and spout for easy pouring. Use by pouring any liquid into the cup and making it level with the desired measurement line.
- When baking precise measurements are important. Baking is more of a science so using the right amount of each ingredient can bring you success. Do not estimate or your recipe may fail.
I hope this article and the handy conversion charts are just what you were looking for. They should help you elevate your cooking skills & ensure your baked goods come out perfect.