How Many Fluid Ounces in a Gallon?
1 gallon = 128 fl oz.
A US gallon is 128 fluid ounces. That is 16 cups of 8 fl oz each, so a half gallon is 64 fl oz and a quart is 32 fl oz. It is handy for working out how many 16-ounce bottles fill a gallon jug: eight.
Gallons to fluid ounces
| Gallons | Fl oz | Cups | Liters |
|---|---|---|---|
| ¼ gallon | 32 fl oz | 4 cups | 0.946 liter |
| ½ gallon | 64 fl oz | 8 cups | 1.89 liters |
| 1 gallon | 128 fl oz | 16 cups | 3.79 liters |
| 2 gallons | 256 fl oz | 32 cups | 7.57 liters |
| 3 gallons | 384 fl oz | 48 cups | 11.4 liters |
| 5 gallons | 640 fl oz | 80 cups | 18.9 liters |
Fluid ounces to gallons
| Fl oz | Gallons |
|---|---|
| 8 fl oz | 0.063 gallon |
| 16 fl oz | 0.125 gallon (⅛ gallon) |
| 32 fl oz | 0.25 gallon (¼ gallon) |
| 64 fl oz | 0.5 gallon (½ gallon) |
| 96 fl oz | 0.75 gallon (¾ gallon) |
| 128 fl oz | 1 gallon |
Counting bottles and servings
Dividing 128 by the container size tells you how many fill a gallon: eight 16-ounce bottles, about 7.5 standard 17-ounce water bottles, or sixteen 8-ounce glasses. For a party punch, a gallon gives about 16 one-cup servings or 21 six-ounce servings. A US gallon is 3.79 liters; the larger imperial gallon is about 153.7 US fluid ounces.
Common questions
How many fl oz are in ½ gallon?
½ gallon = 64 fl oz.
How many gallons is 64 fl oz?
64 fl oz = 0.5 gallon (½ gallon).
How many liters is 1 gallon?
1 gallon = 3.79 liters.
How many ounces of water are in a gallon?
128 fluid ounces. By weight, a gallon of water is about 133.8 ounces (8.36 lb), because water is slightly heavier than one ounce per fluid ounce.