Gallons to Ounces Converter
Convert US gallons (gal) to US fluid ounces (fl oz) instantly. Type a value — the result updates as you type, and the swap button converts the other way.
Gallons to Ounces formula
fl oz = gal × 128
1 US gallon = 128 US fluid ounces · 1 US fluid ounce = 0.007813 US gallons
To convert US gallons to US fluid ounces, multiply the value by 128. For example, 1 gal:
fl oz = 1 × 128fl oz = 128
So 1 gal = 128 fl oz.
Mental math shortcut
This conversion is exact, so there is no need to estimate: just multiply by 128.
Gallons to Ounces conversion table
Ounces back to Gallons
The same values converted the other way, rounded for everyday use:
| US fluid ounces | US gallons |
|---|---|
| 32 fl oz | 0.25 gal |
| 64 fl oz | 0.5 gal |
| 96 fl oz | 0.75 gal |
| 128 fl oz | 1 gal |
| 192 fl oz | 1.5 gal |
| 256 fl oz | 2 gal |
| 384 fl oz | 3 gal |
| 640 fl oz | 5 gal |
About the units
US gallons (gal)
A US gallon is 128 US fluid ounces, exactly 3.785411784 liters. (The UK imperial gallon is 4.546 liters.)
US fluid ounces (fl oz)
A US fluid ounce is 1/128 of a US gallon, about 29.57 ml. (A UK imperial fluid ounce is slightly smaller, 28.41 ml.)
Frequently asked questions
How many US fluid ounces are in a US gallon?
One US gallon equals 128 US fluid ounces.
What is 1 Gallons in Ounces?
1 gal = 128 fl oz.
How do I convert Ounces back to Gallons?
Divide the US fluid ounces by 128.