Convert GALLONS to OZ, Free
Type any GALLONS value and see the OZ result instantly. No button press needed.
How to convert GALLONS to OZ
Gallons and fluid ounces are both US customary volume units, but they live at very different scales. A gallon of liquid is 128 fluid ounces, so converting between them is straightforward multiplication or division by 128. The conversion comes up in cooking, beverage packaging, cleaning product mixing ratios, and any time you need to work at a different scale than the original measurement.
The calculation runs instantly in your browser using JavaScript. Enter the gallon value and the fluid ounce equivalent appears right away.
Enter the gallon amount
Type the number of gallons. Decimals work, so 0.5 gallons or 2.75 gallons are valid inputs.
Read the fluid ounce result
The converter multiplies by 128 and shows the result. 2 gallons = 256 fl oz; 0.5 gallons = 64 fl oz.
Note the value
Copy the result for your recipe, product spec, or mixing guide.
Convert in the opposite direction
Switch to oz-to-gallons if you are starting from fluid ounces and need the gallon equivalent.
Frequently asked questions
How many fluid ounces are in a gallon?
128 US fluid ounces in 1 US gallon.
How many ounces is half a gallon?
64 fluid ounces. Half a gallon is also 2 quarts or 4 pints.
Is this US gallons or UK gallons?
US gallons. 1 US gallon = 128 US fl oz = 3.785 liters. The UK imperial gallon is 160 UK fl oz = 4.546 liters. The units are different.
How do I convert gallons to liters?
1 US gallon = 3.78541 liters. Use a gallons-to-liters converter for that direction.
How many ounces is 5 gallons?
5 x 128 = 640 fl oz.