Food & Drink

How Many Ounces in a Gallon? Complete Conversion Guide

Published on October 6, 2023 | 0 Comments
How many ounces in a gallon?
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Knowing how many ounces in a gallon can help you alter recipes whenever you need to. Our guide gives the facts about how these two quantities compare.

Becoming familiar with how many ounces in a gallon may seem like a straightforward endeavor. But there are specific aspects that can make it tricky to convert from ounces to gallons and back again. When you factor in the difference between U.S. and Imperial measurement, the task gets even trickier.

How do you determine how many ounces are in a gallon? All it takes is a bit of calculation. This helpful guide breaks it down for you, whether you're just beginning to learn to cook or you're a seasoned chef in need of a refresher.


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How Many Ounces in a Gallon?

Determining how many ounces are in a gallon can vary depending on what you're measuring. For example, dry ounces measure differently than fluid ounces. There are differences between U.S. gallons and British-based Imperial gallons to be considered. The sections that follow will provide more detail on each. 

Here's a simple rundown of how many ounces in a gallon for both dry and liquid form. 

  • U.S. dry gallon: 148.947 fluid ounces

  • U.S liquid gallon: 128 fluid ounces

  • Imperial liquid gallon: 153 fluid ounces 

What Is an Ounce?

In the most basic terms, an ounce in standard U.S. weight is equal to 1/16 of a pound for dry substances and 1/16 of a pint for liquid substances. 

In metric measurement, an ounce equals 28 grams. You may see ounces abbreviated as "oz.", which stems from "onza," the Italian word for ounce.  

Fluid Ounces vs. Dry Ounces

Though it might seem like an ounce is an ounce is an ounce, there's an important distinction to make when calculating how many fluid ounces in a gallon versus dry ounces. Knowing the specifics of each type of ounce and how many ounces in a gallon for both types is the key to culinary success.

A fluid ounce is equal to 1/8 of a liquid cup in U.S. measure, as well as 1/16 of a liquid pint. You'll see fluid ounces abbreviated on packaging and in recipes as fl. oz. 

In contrast, a dry ounce is 1/16 of a U.S. pound, and it takes 4.5 dry ounces to equal one U.S. cup.

U.S. Ounces vs. Imperial Ounces

As there are differences between U.S. and British, or Imperial, measurements in general, there are also distinct differences between U.S. and Imperial ounces. According to the American National Standards Institute, a fluid ounce in the U.S. was originally based on a volume of wine, whereas in Britain it was based on a volume of water. With differing densities for each liquid, the idea of an ounce took on two distinct definitions.

A U.S. ounce is defined as 1/16 of a liquid pint, or 29.57353 milliliters, which is rounded to 30 fluid ounces for packaging purposes. Imperial ounces are defined as 1/20 of an Imperial pint, or 28.4131 milliliters. The difference between how many fluid ounces in a gallon for each region may seem minimal, but it can add up to unexpected results.

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What Is a Gallon?

A gallon is a common unit of liquid measure equal to 3.79 liters in U.S. measurement, which converts to 128 ounces. In Imperial measurement, a gallon is equal to 4.54 liters, which converts to 153 ounces.   

Wet Gallons vs. Dry Gallons

While most people are familiar with wet gallons for liquid measurement, there's also the concept of a dry gallon for measuring dry substances in gallon quantities. The difference between the two when it comes to how many ounces in a gallon is considerable, with a wet gallon containing 16 cups and a dry gallon containing 18.62 cups. With a cup equaling 8 fluid ounces, you'll find around 21 extra ounces in a dry gallon when compared to a wet gallon.   

U.S. Gallons vs. Imperial Gallons

U.S. gallons contain slightly more volume than Imperial gallons. A simple way to remember the difference is to memorize that an Imperial gallon is equal to 1.2 U.S. gallons. So in addition to determining how many ounces in a gallon by region, it's also important to know whether your recipe is referencing U.S. or Imperial measurement.

Our Favorite Measuring Tools

Even knowing how many ounces in a gallon, you'll need dependable tools when measuring elements for your favorite dishes or any new recipes that come your way. These include measuring spoons and cups that give you confidence you can count on. Our favorite tools for measuring include:

Once you know how many ounces in a gallon, you can measure confidently when scaling recipes in any direction. If the information seems too slippery to remember, bookmark this guide to use for future reference.

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