Quick Summary: There are 128 fluid ounces in 1 US gallon. To convert gallons to ounces, multiply the number of gallons by 128. So a half gallon = 64 fl oz, 2 gallons = 256 fl oz, and 5 gallons = 640 fl oz. A UK (imperial) gallon is larger and holds 160 imperial fluid ounces.
Conversions are never easy. But it is especially difficult when converting between two different measurement systems.
For example, the United States uses the Imperial system, while Canada and other countries that use it use the metric system.
Don't wonder anymore about how many oz in a gallon. Here is a handy guide on how to convert fluid oz to a gallon or gallons to ounces. Also, enjoy a FREE conversion chart.
Jump to:
- How much water do you need to drink?
- How many fluid ounces in a gallon
- How to convert gallons to ounces
- Gallons to fl oz conversion chart
- What is a gallon?
- US gallon vs. Imperial gallon
- What is a fluid ounce?
- US ounce vs. Imperial ounce
- Fraction of a gallon to ounces conversion chart
- How to convert ounces to gallons
- Ounce to gallon conversion chart
- Other gallon volume conversions
- How many ounces in a gallon of milk
- How many ounces in a gallon of ice cream
- Free printable conversion chart
- Related conversions
- Conclusion
- FAQ
- Comments
How much water do you need to drink?
One of the most common questions is how many ounces of water you should drink a day, and how many gallons that is. Here is the short answer, with the figures converted to ounces and gallons to fit this guide.
According to the Mayo Clinic, the U.S. National Academies of Sciences, Engineering, and Medicine suggest an adequate daily fluid intake of about 15.5 cups (3.7 liters) for men and 11.5 cups (2.7 liters) for women. In ounces, that is roughly 125 fluid ounces a day for men and 91 fluid ounces for women.
Converted to gallons, men need about 1 gallon of water per day (128 fluid ounces), and women about 0.7 gallons (around 91 fluid ounces). One US gallon equals 16 eight-ounce glasses, so a daily goal of one gallon is about sixteen glasses of water.
You may also know the popular "8 by 8" rule, which suggests eight 8-ounce glasses a day, or 64 fluid ounces (half a gallon). It is easy to remember, though the National Academies figures above are slightly higher because they include fluid from all drinks and foods.
These numbers are general guidelines, not a personal target. Real needs change with exercise, hot or dry weather, pregnancy, and overall health, so it is best to ask your doctor how much water is right for you.
Despite seeming complications with all the water and other liquids conversions, I have done conversions for you: from ounces to cups, ounces to quarts, and ounces to pints.
How many fluid ounces in a gallon
Let's dive into how many fl oz make a gallon.
1 gallon to ounces (1 gal to fl. oz.)
One US gallon of liquid equals 128 US fluid ounces, or 1 gal = 128 fl. oz.
One Imperial gallon equals 160 UK fluid ounces, or 1 gal = 160 fl. oz.
1 ounce to a gallon (1 fl. oz. to gal)
How much is one ounce: US and British imperial ounce?
1 US fluid ounce equals 0.0078125 US gallon.
1 Imperial fluid ounce equals 0.00625 Imperial gallons.
How to convert gallons to ounces
To convert US gallons to US fluid ounces, multiply the number of gallons by 128, where 128 is a conversion factor:
the gal x 128.
To convert Imperial gallons to Imperial fluid ounces, multiply the number of gallons by 160, where 160 is a conversion factor:
the gal x 160.
Let's have a look at an example.
How many ounces in 2 gallons?
2 gal x 128 = 256 fl. oz. (US system). So there are 256 US fluid ounces in 2 US gallons.
2 gal x 160 = 320 fl. oz. (Imperial system). So there are 320 Imperial fluid ounces in 2 Imperial gallons.
Let's calculate further. All conversions below are in US fluid measures.
How many ounces in a half gallon
There are 64 f fluid ounces in a half gallon.
How many ounces in 3 gallons
There are 384 fluid ounces in 3 gallons.
How many ounces in 4 gallons
There are 512 fluid ounces in 4 gallons.
How many ounces in 5 gallons
There are 640 fluid ounces in 5 gallons.
Gallons to fl oz conversion chart
The chart below provides an easy-to-use guide to converting US gallons to US fluid ounces.
| Gallons | Fluid ounces | Gallons | Fluid ounces |
|---|---|---|---|
| 1 gal | 128 fl oz | 13 gal | 1664 fl oz |
| 2 gal | 256 fl oz | 14 gal | 1792 fl oz |
| 3 gal | 384 fl oz | 15 gal | 1920 fl oz |
| 4 gal | 512 fl oz | 16 gal | 2048 fl oz |
| 5 gal | 640 fl oz | 17 gal | 2176 fl oz |
| 6 gal | 768 fl oz | 18 gal | 2304 fl oz |
| 7 gal | 896 fl oz | 19 gal | 2432 fl oz |
| 8 gal | 1024 fl oz | 20 gal | 2560 fl oz |
| 9 gal | 1152 fl oz | 30 gal | 3840 fl oz |
| 10 gal | 1280 fl oz | 40 gal | 5120 fl oz |
| 11 gal | 1408 fl oz | 50 gal | 6400 fl oz |
| 12 gal | 1536 fl oz | 100 gal | 12800 fl oz |
Here is another table to convert Imperial gallons to Imperial fluid ounces.
| Gallons | Fluid ounces | Gallons | Fluid ounces |
|---|---|---|---|
| 1 gal | 160 fl oz | 11 gal | 1760 fl oz |
| 2 gal | 320 fl oz | 12 gal | 1920 fl oz |
| 3 gal | 480 fl oz | 13 gal | 2080 fl oz |
| 4 gal | 640 fl oz | 14 gal | 2240 fl oz |
| 5 gal | 800 fl oz | 15 gal | 2400 fl oz |
| 6 gal | 960 fl oz | 16 gal | 2560 fl oz |
| 7 gal | 1120 fl oz | 17 gal | 2720 fl oz |
| 8 gal | 1280 fl oz | 18 gal | 2880 fl oz |
| 9 gal | 1440 fl oz | 19 gal | 3040 fl oz |
| 10 gal | 1600 fl oz | 20 gal | 3200 fl oz |
What is a gallon?
A gallon (abbreviated as "gal") is a measure of volume used in the Imperial and US measurement systems.
The word "gallon" originates from the Latin "galleus" or "galena," which means a container used in the past to measure wine production.
US gallon vs. Imperial gallon
There are two known types of gallons - the US gallon and the Imperial gallon. But what is the difference?
The US gallon is smaller than the UK imperial gallon:
1 US liquid gallon = 3.785 liters or 231 cubic inches;
1 UK gallon = 4.546 liters, or 4 Imperial quarts.
What is a fluid ounce?
An ounce is the name of several different units: a unit of weight measured in dry ounces (oz) or a unit of volume measured in fluid ounces (fl. oz. or fl oz).
US ounce vs. Imperial ounce
The US fluid ounce is larger than the UK fluid ounce used in the Imperial measurement system:
1 US liquid oz = 29.5735 mL
1 UK liquid oz = 28.4131 mL
Fraction of a gallon to ounces conversion chart
This chart provides a simple guide to converting a fraction of US gallons to US fluid ounces.
In the US system, one gallon is 128 ounces, and a half-gallon is 64 ounces. In the Imperial system, there are 160 Imperial fluid ounces in a gallon and 80 Imperial fluid ounces in ½ a gallon.
But how many ounces in ¾, ⅔, ⅓, ¼, and ⅛ gallon?
| Fraction of a gallon | Fluid ounces |
|---|---|
| 1 gal | 128 fl oz |
| ¾ gal | 96 fl oz |
| ⅔ gal | 84 fl oz |
| ½ gal | 64 fl oz |
| ⅓ gal | 42 fl oz |
| ¼ gal | 32 fl oz |
| ⅛ gal | 16 fl oz |
How to convert ounces to gallons
To convert US fluid ounces to US gallons, divide the number of ounces by 128, where 128 is a conversion factor:
the oz ÷ 128.
For example, 1 ounce to gallon calculation:
1 oz ÷ 128 = 0.0078125 gal
To convert Imperial fluid ounces to Imperial gallons, divide the number of ounces by 160, where 160 is a conversion factor:
the oz ÷ 160.
For example, 1 ounce to gallon calculation:
1 oz ÷ 160 = 0.00625 gal
Ounce to gallon conversion chart
Here is a simple unit conversion chart for liquid measurements: from US fluid ounces to US gallons (fl oz to gal) for easy reference.
| Fluid ounces | Gallons | Fluid ounces | Gallons |
|---|---|---|---|
| 1 fl oz | 0.007812 gal | 20 fl oz | 0.15625 gal |
| 2 fl oz | 0.015625 gal | 30 fl oz | 0.234375 gal |
| 3 fl oz | 0.023437 gal | 40 fl oz | 0.3125 gal |
| 4 fl oz | 0.03125 gal | 50 fl oz | 0.390625 gal |
| 5 fl oz | 0.039062 gal | 60 fl oz | 0.46875 gal |
| 6 fl oz | 0.046875 gal | 70 fl oz | 0.546875 gal |
| 7 fl oz | 0.054687 gal | 80 fl oz | 0.625 gal |
| 8 fl oz | 0.0625 gal | 90 fl oz | 0.703125 gal |
| 9 fl oz | 0.070312 gal | 100 fl oz | 0.78125 gal |
| 10 fl oz | 0.078125 gal | 1000 fl oz | 7.8125 gal |
Other gallon volume conversions
Here is a quick conversion chart from one gallon (1 gal) to other US volume units, otherwise specified.
| Units | Number of units |
|---|---|
| Quarts | 4 qt. |
| Pints | 8 pt. |
| Cups (US) | 16 cups US |
| Cups (Imperial) | 13.33 cups U. K. |
| Tablespoons | 256 tbsp |
| Teaspoons | 768 tsp |
| Liters | 3.79 L |
| Milliliters | 3785.41 mL |
How many ounces in a gallon of milk
There are 128 US fluid ounces in a gallon of milk sold in supermarkets in the United States. In the UK, there are 160 UK fluid ounces in a British gallon of milk.
How many ounces in a gallon of ice cream
Getting ready for a potluck or BBQ party? You will need to buy a large amount of ice cream, like a gallon, for example, that yields about 32 scoops. One scoop equals 4 ounces.
How many ounces are in a gallon of ice cream? A true gallon of ice cream contains 128 ounces, but surprisingly, some containers are labeled as a gallon that contains about 96 ounces.
Free printable conversion chart
I am so excited to share this FREE kitchen conversion chart with you. It will help make baking more accessible and more fun.
Download this handy Kitchen Conversion Chart >>
Related conversions
Be sure to also check out other baking conversion charts on the website:
- Grams To Cups Conversions
- Cups To Grams Conversions
- How Many Cups In A Pint
- How Many Cups In A Gallon
- How Many Milliliters In A Teaspoon
- How Many Milliliters In A Tablespoon
- How many ounces in a quart
Also, you will fall in love with this simple tool, Cake Pan Converter, to calculate cake pan sizes.
Conclusion
I hope this guide has brought you joy and an educational experience to help you get started in the kitchen. Or it has made another step towards becoming a better baker.
You might see other frequently asked questions about a gallon to ounces conversion, for example:
- How many oz in a gallon
- How many fluid ounces in a gallon
- How many fl oz in a gallon
- How many ounces in one gallon
- How many ounces are in 1 gallon
- How many ounces per gallon
- 1 gallon equals how many ounces
The answer is the same: 1 gallon equals 128 fluid ounces.
FAQ
How many ounces are in a gallon of water?
There are 128 fluid ounces of water in a US gallon. In the UK, a gallon of water equals 160 imperial fluid ounces.
Is 1 gallon the same as 64 oz?
No. One gallon equals 128 fluid ounces, while 64 US fl oz make ½ gallon.
How many 8 oz bottles make a gallon?
One gallon contains 128 ounces, so 8 eight-ounce bottles make a gallon.
How many 16 oz in a gallon?
Eight 16 oz make a gallon.
How many 16 oz bottles make a gallon?
One gallon contains 128 ounces, so eight 16-oz bottles make a gallon.
How many 16.9 oz bottles make a gallon?
To be precise, there are 7.574 16.9 oz bottles in a gallon.
How many 32 oz make a gallon?
Four 32 oz make a gallon.
How many 32 oz bottles make a gallon?
One gallon is 128 ounces, so four 32-oz bottles make a gallon.
How many ounces in a half gallon?
There are 64 fluid ounces in a half-gallon.
How many gallons do 64 ounces equal?
64 fluid ounces equal ½ gallon.
How many glasses of water in one gallon?
One gallon contains 128 ounces, and a standard glass holds 8 ounces. So 16 eight-ounce glasses of water make one US gallon.
How many cups in a gallon?
There are 16 cups in a gallon, because 1 measuring cup equals 8 fluid ounces. See how many cups in a gallon for more.
Aly says
Thank you for this valuable information.