Convert US gallons to US fluid ounces
Converting US gallons to US fluid ounces is a common volume task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 gal equals 128 fl oz, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert US gallons to US fluid ounces
To convert US gallons to US fluid ounces, multiply the number of US gallons by 128. For example, 10 gal × 128 = 1,280 fl oz.
fl oz = gal × 128
- Write down the value in US gallons you want to convert.
- Multiply it by 128 (the exact gal→fl oz factor).
- The result is your value in US fluid ounces. Check it below with the converter or the table.
Conversion table
Common values of US gallons and their equivalents in US fluid ounces:
| gal | fl oz |
|---|---|
| 1 | 128 |
| 2 | 256 |
| 3 | 384 |
| 4 | 512 |
| 5 | 640 |
| 10 | 1,280 |
| 20 | 2,560 |
| 25 | 3,200 |
| 50 | 6,400 |
| 100 | 12,800 |
| 250 | 32,000 |
| 500 | 64,000 |
About these units
US Gallon (gal). The US liquid gallon is defined as exactly 3.785411784 liters, or 128 US fluid ounces. Fuel economy and milk containers in the United States use gallons.
US Fluid Ounce (fl oz). The US fluid ounce is exactly 1/128 of a US gallon, or 29.5735295625 milliliters. Beverage cans, cosmetic bottles and cocktail recipes use fluid ounces.
Frequently asked questions
How do I convert US gallons to US fluid ounces?
To convert US gallons to US fluid ounces, multiply the number of US gallons by 128. For example, 10 gal × 128 = 1,280 fl oz. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many US fluid ounces are in 1 us gallon?
1 gal = 128 fl oz. That is the fixed relationship used by this converter and by international standards.
How many US gallons are in 1 us fluid ounce?
1 fl oz = 0.0078125 gal. If you are converting in the opposite direction, use our US Fluid Ounce to US Gallon converter for the dedicated table and FAQ.
Is the US gallons to US fluid ounces conversion exact?
Yes. Both units are defined by international agreement, so the factor of 128 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is us gallon used for?
The US liquid gallon is defined as exactly 3.785411784 liters, or 128 US fluid ounces. Fuel economy and milk containers in the United States use gallons.