Looking for an answer to how many ounces are in a gallon? This easy conversion chart will break it all down for you and make kitchen measurements a breeze!
How many ounces are in a gallon?
There are 128 fluid ounces in a gallon.
However, it can vary depending upon liquid or dry gallons and the system of units used. In dry US gallons, there are 148.94545 ounces.
If you use the British Imperial system, then there are 153 fluid ounces in 1 Imperial gallon.
An important thing to note is that the United Kingdom only uses the British Imperial system for gallons. For almost all other measurements, they use the metric system (like measuring how many grams are in a cup).
What is a gallon?
A gallon is a unit of volume in both the Imperial and U.S. customary systems and is a unit of capacity for liquid volume. The abbreviation for gallon is “gal,” and it’s different from ounces.
We explain this in further detail when discussing liters to gallons conversions.
Ounces to gallons conversion
The formulas for converting ounces to gallons differ if you’re using the British or US customary system. The following conversion formula is useful if you have US units.
Convert ounces to gallons = fluid ounces ÷ 128
If you are dealing with the Imperial conversion system, the following formula will be used to find gallons:
Convert ounces to gallons (Imperial) = fluid ounces ÷ 153
Here is a quick conversion chart for your convenience:
| 8 fl oz | 1/16 gallon |
| 16 fl oz | ⅛ gallon |
| 32 fl oz | ¼ gallon |
| 64 fl oz | ½ gallon |
| 128 fl oz | 1 gallon |
Note: All the conversions in the table are in US liquid measurements.
Measuring an ounce and gallon internationally
Now, you know that if you’re in the United States, there are 128 fluid ounces in a gallon. However, there are other countries that use a different measurement, so you need to know how to measure an ounce and gallon internationally.
Using the British Imperial system, 1 UK gallon equals 1.2 US gallons or 153.6 fluid ounces. Many changes have occurred in the Imperial gallon over time, and the value was changed anywhere between 129 to 163 ounces.
In Canada, New Zealand, Australia and South Africa, the metric system is more common than Imperial gallons and ounces. In the United States, the Imperial system is used for almost everything.
Wet vs dry gallons
Wet vs dry gallons aren’t the same and you need to know the difference.
A dry gallon equals to ⅛ of a bushel or 231 cubic inches. A dry gallon isn’t used as often as the liquid gallon and is larger than the size of the liquid gallon. The general conversion is the same for both dry and wet gallons and you get 4 quarts in a gallon, 2 pints in a quart, and 2 cups in a pint.
How many ounces in a half gallon?
There are 64 fluid ounces in a half gallon.
How many ounces in a quarter gallon?
A quarter gallon contains 32 fluid ounces.
More measurement resources
- How many cups in a quart
- How many teaspoons in a tablespoon
- How many tablespoons in a cup
- Ounces in a cup
- How many quarts in a gallon
Frequently Asked Questions
No, 1 gallon isn’t the same as 64 ounces because there are 128 ounces in 1 gallon.
A gallon of water is equal to 128 fluid ounces.
Eight 16 oz bottles of water will be equal to a gallon.
There is 0.25 gallons in 32 ounces.
Yes, 128 ounces make 1 gallon, so they are the same.
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