The quick answer to how many ounces are in a gallon of water is 128 fluid ounces. But there is more information behind this measurement. Understanding ounces, fluid ounces, gallons, etc. can be overwhelming at times, but these measurements need to be accurate, especially if you are a chef, cook, or baker.

**What Is a Gallon?**

The gallon is a unit to measure volume. The United States uses gallons, quarts, pints, cups, tablespoons, teaspoons, and fluid ounces to measure volume. A gallon is equal to 8 pints, 4 quarts, or 16 cups. Its abbreviation is *gal*. The term *gallon* is derived from *galon*, which means "pail," and was taken from either old French or Latin.

**What Is a Fluid Ounce?**

A fluid ounce is also a unit to measure volume. It is abbreviated as *fl oz*, and it equals ⅛ of a cup or 29.57 ml.

Fluid ounces are different from ounces. Ounces measure weight, such as with a kitchen scale. Fluid ounces measure volume, or the amount of space the ingredient takes up. Fluid ounces are measured with a marked measuring cup.

**How Many Ounces Are in a Gallon of Water?**

Based on the information above, the correct question is how many fluid ounces are in a gallon of water. There are 128 fluid ounces in a gallon of water.

1 gallon (gal) of water = 128 fluid ounces (fl oz)

**How many 16.9-ounce bottles are in a gallon of water?**

It is easy to visualize gallons and fluid ounces using products that are common in our environment. You may drink bottled water daily. A standard bottle of water is 16.9 fluid ounces. You will need 7.574 standard water bottles to make one gallon.

128 fl oz ÷ 16.9 fl oz = 7.574 water bottles

1 gallon = 128 fl oz = 7.574 bottles of water (16.9 fl oz each)

**Converting Between Gallons and Fluid Ounces**

### Gallons to Fluid Ounces

### Gallons(gal) to Fluid Ounces(fl oz)

Type the volume in gallons below to get the value converted to fluid ounces.

Ounces(fl oz):

To convert gallons into fluid ounces, you multiply the number of gallons by 128.

Number of fluid ounces = Number of gallons × 128

For example, if you want to know how many fluid ounces are in 6 gallons, you multiply 128 by 6.

Number of fluid ounces = Number of gallons × 128

Number of fluid ounces = 6 × 128

Number of fluid ounces = 768

So, there are 768 fluid ounces in 6 gallons.

### Fluid Ounces(fl oz) to Gallons(gal)

### Fluid Ounces(fl oz) to Gallons(gal)

Type the volume in fluid ounce below to get the value converted to gallons.

Gallon(gal):

To convert fluid ounces into gallons, you divide the number of fluid ounces by 128.

Number of gallons = Number of fluid ounces ÷ 128

For example, if you want to know how many gallons are in 640 fluid ounces, you divide 640 by 128.

Number of gallons = Number of fluid ounces ÷ 128

Number of gallons = 640 ÷ 128

Number of gallons = 5

So, there are 5 gallons in 640 fluid ounces.

**Conversion Table for Gallons and Fluid Ounces**

Gallons (gal) | Fluid Ounces (fl oz) |

¼ gal | 32 fl oz |

½ gal | 64 fl oz |

1 gal | 128 fl oz |

2 gal | 256 fl oz |

3 gal | 384 fl oz |

4 gal | 512 fl oz |

5 gal | 640 fl oz |

10 gal | 1280 fl oz |

**Bottom Line**

So the answer to how many ounces are in a gallon of water is 128 fluid ounces. Understanding both gallons and fluid ounces can be helpful when measuring liquids.