How many ounces are in a gallon?

How many ounces are in a gallon?

How many ounces are in a gallon?

What is Ounce?

The ounce is the name of several different units of mass, weight, or volume used in most British derived customary systems of measurement.

The common avoirdupois ounce (approximately 28.3 g) is ​1⁄16 of a common avoirdupois pound; this is the United States customary and British imperial ounce.

It is primarily used in the United States to measure packaged foods and food portions, postal items, areal density of fabric and paper, boxing gloves, and so on, but is sometimes also elsewhere in the Anglosphere.

What is Gallon?

The gallon is a unit of measurement for volume and fluid capacity in both the US customary units and the British imperial systems of measurement. Three significantly different sizes are in current use:

  • The imperial gallon (imp gal), defined as 4.54609 litres, which is used in the United Kingdom, Canada, and some Caribbean nations;
  • The US gallon (US gal) defined as 231 cubic inches (exactly 3.785411784 litres), which is used in the US and some Latin American and Caribbean countries; and
  • The US dry gallon (“usdrygal”), defined as ​1⁄8 US bushel (exactly 4.40488377086 litres).
  • There are four quarts in a gallon and eight pints in a gallon, and they have different sizes in different systems.

The IEEE standard symbol for both US (liquid) and imperial gallon is gal, not to be confused with the gal (symbol: Gal), a CGS unit of acceleration.

How many ounces are in a gallon?

The answer to your question of how many ounces (oz) there are in a gallon of water depends on where in the world you are. You see, the US liquid gallon measures less (3.785 liters) than the UK imperial gallon (4.546 litres).

You should probably bear this in mind when thinking about daily water intake because there’s a big difference between the two (you could be drinking 3/4 of a litre more water if you use the UK imperial gallon conversion). If you want the conversion in cups, by the way, do take a look at this post on gallons and cups.

When converting to ounces (fluid ounces), you need to bear in mind that the US fluid ounce measures more than the UK imperial fluid ounce. The US fluid ounce measures 29.5735mL . By comparison, the UK (imperial) fluid ounce measures 28.4131mL. To assist you, I’ve included the two conversions of gallons to ounces below.

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

How Do Both Systems Work?

Both the US and the UK liquid customary measurements systems take the fluids by volume and divide them into 4 parts. However, the major difference is the calculation. While the US measurements system says a gallon is 128 ounces, a UK system defines a gallon is 160 ounces. Now, there is a major difference here. Even though both systems use gallons, ounces, pints, and quarts, they use different volume measurements. To summarize this, the UK gallon is about 20% larger than the US gallon.

Gallons to ounces conversion tables

I’ve included two table of conversions to help you see how many fluid ounces there are in a gallon – one using US and one using UK measurements. 

Gallons (US)Ounces (US)Liters
Gallons (UK)Ounces (UK)Litres

How many 32 ounces are there in a gallon of water?

One gallon is 128 ounces, so that’s four times 32 ounces. 32 ounces is one quart, meaning one quarter of a gallon. 64 ounces is a half-gallon, also known as two quarts. 96 ounces is three quarts. 16 ounces (half a quart) is one pint.

8 ounces (half a pint) is one cup. All of this refers to measurements used in the USA. UK (Imperial) gallons and quarts are bigger than American ones. Also note that a fluid ounce (a unit of volume) is not necessarily he same as an ounce of weight. Furthermore, dry quarts are not the same size as liquid quarts. The numbers I’ve given are for liquid measures.

The above may give you a hint as to why most countries have switched to the Metric (International) system of measurements.

How many 16 oz water bottles are in a gallon?

It depends what sort of gallon and (fluid) ounce you’re talking about. A US gallon (approx. 3.8 litres) is 128 US fluid ounces. So that’s 8 bottles.

However, the US gallon and US fluid ounce are different to the Imperial gallon and fluid ounce that are used elsewhere in the world if not using S.I. units. The Imperial gallon is about 25% bigger at approx. 4.5 litres. And the Imperial fl.oz is about 4% smaller than the US equivalent.

So an Imperial gallon is 160 Imperial fl. oz. which means 10 bottles.

How many ounces in a pound?

It depends on the type of pound you are using. One pound of Avoirdupois weight consists of 16 ounces. There are 12 ounces in a pound of apothecary weight and 12 ounces in a pound of Troy weight. In the US, the Avoirdupois unit is the model, making the US pound equivalent to 16 ounces.

To put the pound in cooking perspective, a flavorful Burger King Whopper measures around 10 ounces (before being prepared, of course), which only covers half a pound of meat.

The multi-talented Google also enables its services as an online calculator. Go to and insert the text “how many ounces are there in a pound?” and click the “Search” button. Google realizes that its calculator can answer your question, so it returns the answer “1 pound equals 16 ounces.



How many ounces in a gallon?

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)


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Ounces To Gallons Conversion Chart
How Many Ounces In A Gallon Canadian
How Many Ounces In A Gallon Of Water

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