How many fluid ounces are in one US gallon?
One US gallon is 128 fl oz.
US Gallons to Fluid Ounces
Type a value to convert it from US gallons to fluid ounces. One gal equals 128 fl oz.
Result
US gallons and fluid ounces, side by side
One US gallon is 128 fl oz. In the other direction, one fluid ounce is 0.007813 gal.
Both belong to the imperial and US system, linked by a fixed whole-number ratio rather than by measurement, so the conversion is exact.
The US gallon is exactly 231 cubic inches, about 3.785 liters, and prices gas and milk in the United States. The imperial gallon used in the United Kingdom is larger, about 4.546 liters, so a gallon is not the same on both sides of the Atlantic.
The US fluid ounce is one 128th of a US gallon, about 29.57 milliliters, and a standard American can holds 12 fl oz. The British imperial fluid ounce is slightly smaller, about 28.41 ml, and neither has anything to do with the ounce of weight.
| Gallon (US) | Fluid ounce |
|---|---|
| 1 | 128 |
| 2 | 256 |
| 5 | 640 |
| 10 | 1,280 |
| 20 | 2,560 |
| 50 | 6,400 |
Frequently asked questions
How do I convert fluid ounces back to US gallons?
One fluid ounce is 0.007813 gal. The tool above converts in both directions.
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