How Many Ounces In a Gallon?


Are you aware of how many ounces in a gallon of water?

Don’t you know the answer? Or still not sure?

Well, there are different measurement units in various things. So, we would need to know the density of the substance before we could answer the question.

Generally, one important thing to remember about convert ounces to gallons is that there are 128 ounces in each gallon.

1 Gallon = 128 oz(Ounce) US

How Many Ounces In a Gallon
illustration by Artist Prashant Maru
  • A gallon is a unit of volume measurement in the US customary and imperial systems, abbreviated as “gal”.
  • A fluid ounce is a unit of volume in the US customary and imperial systems of measurement abbreviated as “fl. Oz”. A small quantity or portion.


1350–1400; Middle English unce < Middle French < Latin uncia twelfth part, inch, ounce, a derivative of unusone, (Courtesy:

An important thing is to be noted that fluid ounces and weight ounces are not similar. Liquid ounce measurement indicates the volume of the liquid, while dry ounce measurement records the weight.

But the confusion is not over. There is a total of three players in this game

  • 1 Gallon (Fluid, US) = 128 Ounces (Fluid, US)
  • 1 Gallon (Dry, US) = 148.94684 Ounces (Fluid, US)
  • 1 Gallon (UK) = 160 Ounces (UK)

How many ounces in a gallon?


let’s go-ahead

While using an intermediate unit for an easy conversion by using the equivalence method. We’ll use grams as it’s a smaller and prior unit to both the quantities.

Before we go ahead, lets first clear out the number of grams in terms of ounces and gallons.

Ounces in grams

An ounce is a very small quantity. Mainly for the number of sensitive things like liquid medicine or chemicals.

Like one should be used in drinks. And coming to grams, it is equivalent to an exact 28.3495 grams. Little long fractional unit but exact to the value.

Gallons in grams

One gallon is a large unit for grams, even more than 3 times as bigger as a kilogram. One gallon seems mostly equal to 3.785 kg or more accurately it is equal to 3785.41179 gms. Another big fractional number it is.

So how many ounces in a gallon?

Now we are very clear and already know the full numbers of grams in an ounce and a gallon.

You have finite numbers and we just have to convert it from one unit to the other using the unitary way. The easiest method. It is easy, isn’t it?

So, total grams in one oz is 28.3495. and in one gallon is 3785.41179. Hence the total amount of ounces in a gallon will be equal to 3785.41179 divided by 28.3495 gives us 133.52658. And it is the sure figure of the number of ounces in a single gallon.

So, how many ounces in a gallon? 133.52658 (up to 5 decimal places exact)

Now let’s see how many fluid ounces in one gallon

Still little tricky as here we have fluid ounces. Both two are not the same. As one oz is equal to 28.3495 gms. While fluid ounce is equivalent to 29.57353 gms.

The relation in between number and conversion units, with a fraction of 1/1000 or 0.001 becomes 1 when used with bigger conversions like 1000.

The amount of fluid ounces in a gallon is equal to 3785.41179 gms divided by 29.57353 gms gives us a total of 127.999998 oz. Means a simple 128 oz.

How to calculate differences in an easy way?

Let’s find out…

How Many Ounces In a Gallon

One gallon contains 4 quarts, which is also equivalent to 8 pints or 16 cups of liquid. Now we know there is 128 oz in one-gallon means 16 cups is equal to one gallon. A cup is 8 oz. So, there are 128 ounces in a gallon of water.

Now let’s see an example

How we can find how many ounces of milk weighs in one gallon?

gallon weight of milk


  • 1 gallon = 128 fl oz
  • 1 pound = 16 fl oz
  • 16 oz = 1 lb
  • 1 oz = (1/16) lb
  • 128 oz = (1/16) X 128 = 8

Now let’s understand this calculation. As we can never be sure about the sure weight so the answer is always in a decimal. Milk is a natural or organic product and the present of the fat in milk, the weight can be varied at different times.

1 liquid gallon is equal to 128 fl oz. Means that one gallon is equal to mostly 16 cups as we saw above and 128 fl oz is equal to 4 liquid quarts. Now we can calculate how much is in 1 pound.

Then, divide 1 by 16. And multiply with 128 fluid ounces. So, the answer will be ready as there are more than 8 pounds in a gallon of milk. Little more than 8 because of its density of the fat content. Useful? Yes, it is!

Let’s begin with another way with some practical examples


A small glass holds about 8 fluid ounces, called 1 cup

1 cup = 8 fl oz

1 cup = 8 fl oz


A pint is equal to 2 cups (example: a large glass of milk)

1 pint = 2 cups = 16 fl oz


One quart (qt) is equal to 2 pints or 4 cups.

1 quart = 2 pints = 4 cups = 32 fluid ounces


One gallon is the same as 16 cups or 8 pints or 4 quarts. The largest liquid measurement.

1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces

Fluid Ounce  

A unit of capacity equal to 1/8 of a cup. One fluid ounce of water at 62°F weighs about one ounce. The amount of liquid medicine is often measured in fluid ounces.


A unit equal to 8 fluid ounces. The capacity of a standard measuring cup is one cup


A unit equal to 16 fluid ounces, or 2 cups. The capacity of a carton of ice cream is often measured in pints.


A unit equal to 32 fluid ounces, or 4 cups. You often see quarts of milk being sold in the supermarket.


A unit equal to 4 quarts, or 128 fluid ounces. When you fill-up your car with gasoline, the price of gas is often listed in dollars per gallon

Need more gallon volume Conversions conversation? Here it is

  • 1gal = 0.003785 cubic meters
  • 1gal = 3,785 cubic centimeters
  • 1gal = 0.004951 cubic yards
  • 1gal = 0.133681 cubic feet
  • 1gal = 230.999493 cubic inches
  • 1gal = 3,785 milliliters
  • 1gal = 3.785412 liters
  • 1gal = 768 teaspoons
  • 1gal = 256 tablespoons
  • 1gal = 16 cups
  • 1gal = 8 pints
  • 1gal = 4 quarts

Quick Reference

1% per one gallon = 1.28 Ounces (oz) or 2.56 Tablespoons (Tbsp)
2% per one gallon = 2.56 Ounces (oz) or 5.12 Tablespoons (Tbsp)
1% per 2 gallons = 2.56 Ounces (oz) or 5.12 Tablespoons (Tbsp)
2% per 2 gallons = 5.12 Ounces (oz) or 10.24 Tablespoons (Tbsp)
10% per one gallon = 12.8 Ounces (oz) or 1.58 Cups (c)

Some Examples of Usage of Gallons and Ounces

Let’s find out the use of gallons and ounces in an industrial way, here we have one example to understand it.

How many ounces of almonds go into making each half-gallon of almond milk? (Example ‘So Delicious Almond milk’ brand)

Around 2 cups of almonds are being used to make a half-gallon of almond milk but made the same way as coffee by straining water through the ground beans, so we aren’t eating much of the almond. Mostly is water. (As the almond content of the milk is around 2% so we are drinking is almond-flavored water)

Also, unsweetened almond milk should have about 360 calories per half a gallon. If we have less, it’s because of watered down. The sweetened variety should be more than double that number of calories.

What is the Average Number of Scoops in a 3 Gallon Container of Ice Cream?

Gallon Container of Ice Cream

Do you know what number of scoops of ice cream in a 3-gallon Jar?

Let’s solve it

It’s necessary to calculate the exact math for profit margins when we start ice-cream, parlor business. So, all we need is the right calculation for everything.

The question sounds easy, but we have to be alert for mixing measures of volume with measures of weight. (As we already discussed it earlier) One thing we have to be sure that all different ice creams have different densities.

For example, lower-grade ice cream has less butterfat and more air, So, that will produce fewer OZ scoops than, say, a 3-gallon container of premium ice cream that is denser.

Moreover, if we are measuring volume (cups & gallons vs. ounces & gallons) the question becomes easier.

If the scoop is 5 oz size, there are 96 scoops of ice cream (As per earlier method for counting them) in a 3-gallon jar. However, we might want to trim that down by a scoop to accommodate for any ice cream lost in sampling and serving.

To calculate via 5-ounce scoops would require we know the density of the ice cream we are planning to serve. It will likely range based on the type of ice cream as mentioned earlier.

I hope after knowing this fact we will have a better idea for measurements for our daily life hacks as well as business profit margins or calculations.

Some interesting facts

Hey, do u know? To produce 1 gallon of wine, it requires 872 gallons of water. But if you want standard servings, and when we look deeper it’s 34 gallons of water needed for 5 fluid ounces of wine.

Tea requires about 108 gallons of water per gallon of brewed tea. It is interesting, isn’t it?

Pasta consumes about 222 gallons per pound. While rice requiring 299 gallons of water per pound of processed rice.

Bananas, grapes, cactus, and kiwis all need less than 100 gallons per pound while Strawberries, watermelon, and pineapple require less than 50 gallons of water per/lb of fruit.

Chocolate requires an average of more than 2,000 gallons per pound. Sadly, it takes more water to produce than beef. Now you’ll be eating a pound of chocolate soon, lol.

(Note: Above facts reports were taken as reference study from Water Footprint Network’s website )


Let’s play a puzzle now

One milkman has 2 empty jugs, one 3-gallon jug, and a 5-gallon jug. How will he measure exactly 1 gallon or how many ounce milk without wasting any of them?

Do you have any idea how can we solve it? Then let’s do it…

  1. Fill the all 3-gallon jug with milk.
  2. Now, pour it all in the 5-gallon jug.
  3. Fill the 3-gallon jug again.
  4. Pour it in the 5-gallon jug.
  5. As 3-gallons of milk is already there in it, we’ll fill the remaining 2-gallon of milk.
  6. Now we’ll be left with 1-gallon milk in the other jug.

It means 128- fl ounce milk we will have left in that jug as

1-gallon = 128 fl oz.

How was it? Cool? Yeah, it is… 😊


Another one

How do we calculate how many 16.9 oz water bottles equal to one gallon?

Before begin to solve it, we need to break down the conversion ratios first. as we want to convert ounces into gallons to know how many water bottles are required.

  • First of all 1 Gallon of water has 128 fluid ounces. (US)

So, we divide 128 ounces by the 16.9-ounce size of the water bottle.

It’s 128/16.9 = 7.5739645 oz

Now, let’s go ahead. There is 128 oz in one gallon. So, divide 128 by 16.9 and have your answer. So that would be 7.57 bottles of water in a gallon.

Finally, we need at least 8 bottles to have enough to fill a gallon !!!



So, How Many Ounces In A Gallon?

  • US ounces to gallons = 128 fluid ounces = 1 fluid gallon
  • UK ounces to gallons = 160 fluid ounces = 1 fluid gallon

That’s it. Thank you for your visit 😊