How Many Ounces (oz) there are in a Gallon of water depends on where in the world you are. This is essentially true given that different countries use different SI units to measure the mass and volume.

Unfortunately, it isn’t easy to calculate a gallon. That’s why everyone would want to know “how many glasses of water make a gallon?”

## How Many Ounces Are in a Gallon?

First things first: To do the calculations, you need to know what capacity a gallon holds.

Usually, a gallon holds 3.8 liters or 128 ounces, 4 quartz or sometimes written as 128 oz.

This implies that a gallon holds 16 glasses of water and a glass is 8 ounces.

Still, it can get tricky to know how many ounces are in a gallon because it depends on the system of calculation one is using and the country as well.

This is essentially true given that different countries use different SI units to measure the mass and volume.

For instance, the Gallon is the unit of capacity in imperial and U.S. standard frameworks. Multiple countries have however swapped gallon with liter.

That means, when measuring a gallon, it depends on the system one is using.

Ideally, the usual system of measurements used are the UK and U.S system of measurement.

### Ounces to Gallons

**U.S system of measurement**: 1-Gallon equals 128 ounces according to the US system of measurement.

**Calculated as: 1 Gallon = 128 Ounces.**

**UK system of measurement**: 1-Gallon equals 160 ounces according to the UK system of measurement.

**Calculated as: 1 Gallon = 160 Ounces.**

The US system of measurement is a variation of the UK imperial system. And perhaps the fact that these two SI units were adopted by many countries is because of the power, popular, and reach the two countries (the UK and US) have over the world.

### Now calculating ounces in 1-gallon to liter

**The US system**

1 Gallon of US fluid equals to 3.785 liters

Calculated as: 1 Gallon (US, Fluid) = 3.785 liters

1 liter equals to 33.814 ounces of US fluid

Calculated as: 1 Liters = 33.814 oz. (US fluid)

1 fluid Gallon would be 3.785 multiplied by 33.814 which equals 128 ounces

Calculated as: 1 fluid Gallon= 3.785 X 33.814 = 128oz.

**The UK system**

1 Gallon of UK fluid equals 4.54609 liters

Calculated as: 1 Gallon (UK, Fluid) = 4.54609 liters

1 Liters equals 35.1951 ounces of UK fluid

Calculated as: 1 Liters = 35.1951 ounces (UK fluid)

1 fluid Gallon equals 4.54609 multiplied by 35.1951 which equals 160 ounces.

Calculated as: 1 fluid Gallon = 4.54609 x 35.1951 = 160 oz.

That means, to calculate how many ounces are in a gallon, you will finalize your calculations by simply doubling the ounces for every gallon increase; and this applies to the U.S and UK system of measurement.

## Ounces to Gallons Conversion Tables

Gallons (US) |
Ounces (US) |
Gallons (UK) |
Ounces (UK) |

1 | 128 | 1 | 160 |

2 | 256 | 2 | 320 |

3 | 384 | 3 | 480 |

4 | 512 | 4 | 640 |

5 | 640 | 5 | 800 |

6 | 768 | 6 | 960 |

7 | 896 | 7 | 1120 |

8 | 1024 | 8 | 1280 |

9 | 1152 | 9 | 1440 |

10 | 1280 | 10 | 1600 |

11 | 1408 | 11 | 1760 |

12 | 1536 | 12 | 1920 |

13 | 1664 | 13 | 2080 |

14 | 1792 | 14 | 2240 |

15 | 1920 | 15 | 2400 |

*Data Source: www.thecalculatorsite.com*

**See this reference Video of How many Ounces in a Gallon?**

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