Convert Ounces to Gallons (oz to gal): Chart, Formula, Steps, FAQs

Home » Math Vocabluary » Convert Ounces to Gallons (oz to gal): Chart, Formula, Steps, FAQs

What Is Ounces to Gallons Conversion?

Ounces to gallons conversion is the conversion of liquid volume measurement given in fluid ounces into its gallon equivalent.

1 US gallon $= 128$ US fluid ounces

Gallon and fluid ounce are the units of measurement for liquid volume or capacity in the US customary system of measurement.

You can convert Ounces to Gallons instantly using this online calculator without any need to do your own calculations.

How to Use the Ounce to Gallons Conversion Calculator

  • Open the calculator.
  • To convert a measurement given in ounces into gallons, type in the number of ounces in the box labeled “Ounces.”
  • The equivalent value in the US Gallons will automatically show up in the box mentioned in front of the “Gallon.”

Although you can convert ounces into gallons by using easy online converters, here is how you can do it by applying a simple formula!

What Is a Fluid Ounce?

A fluid ounce (abbreviated fl oz) is a unit of liquid volume or capacity.

1 fl oz $= \frac{1}{20}$ of a pint $= \frac{1}{160}$ of an Imperial gallon $= \frac{1}{16}$ of a US liquid pint $= \frac{1}{128}$ of a US gallon 

  • 1 US fluid ounce $= 0.0078125$ gallon. 
  • 1 Imperial fluid ounce $= 0.00625$ gallon

Given below are some common conversions from US fluid oz to gallons:

16 oz $= 0.125$ gallon
24 oz $= 0.1875$ gallon
32 oz $= \frac{1}{4}$ gallon
64 oz $= \frac{1}{2}$ gallon
96 oz $= \frac{3}{4}$ gallon
128 oz $= 1$ gallon

What Is a Gallon?

A gallon (gal) is a customary unit of volume and capacity for liquid measure. 

1 gallon $= 8$ pints $= 3.785$ liters

It is also used in the imperial system of measurement. The American gallon is a smaller unit of volume and has a different conversion factor.

  • 1 US gallon $= 128$ US fl oz
  • 1 Imperial gallon $= 160$ imperial fl oz

Ounces to Gallons Formula

1 US gallon $= 128$ fluid ounces.

1 fluid ounce $= \frac{1}{128}$ gallons $= 0.0078125$ gallons

Thus, to convert gallons to fluid ounces, divide by 128 or multiply by 0.0078125.

Thus, the formula to convert ounces to gallons can be given as 

  • Gallons $=$ fluid ounces $\div 128$
  • Gallons $= 0.0078125$ fluid ounces   

Note:

If you are dealing with the Imperial conversion system, the following formula will be used to find gallons:
Gallons $=$ Fluid ounces $\div 160$

How to Convert Ounces to Gallons

Converting ounces to gallons is easy! First, you need to know how many gallons are to an ounce!

There are 0.0078125 gallons per ounce. 

1 fluid ounce $= 0.0078125$ gallons 

Therefore, to convert a measurement in fluid ounces to a measurement in gallons, multiply the ounce value by 0.0078125 (or divide by 128 as 1 gallon = 128 fluid ounces).

You can use the following two formulas to convert ounces to gallons:

  • Gallons $=$ fluid ounces $\div 128$
  • Gallons $= 0.0078125$ fluid ounce

Example: Convert 20 ounces to gallons. 

Simply divide the amount you have (20 ounces) by the conversion factor (128).

$20 \div 128 =  0.15625$ Gallon

OR

Multiply the amount you have (20 ounces) by the conversion factor (0.0078125) 

20 ounces $ \times 0.0078125 = 0.15625$ gallon

Ounce to Gallon Conversion Table

Fluid OuncesGallons
1 fl oz0.007812 gal
2 fl oz0.015625 gal
3 fl oz0.023437 gal
4 fl oz0.03125 gal
5 fl oz0.039062 gal
6 fl oz0.046875 gal
7 fl oz0.054687 gal
8 fl oz0.0625 gal
9 fl oz0.070312 gal
10 fl oz0.078125 gal
20 fl oz0.15625 gal
30 fl oz0.234375 gal
40 fl oz0.3125 gal
50 fl oz0.390625 gal
60 fl oz0.46875 gal
70 fl oz0.546875 gal
80 fl oz0.625 gal
90 fl oz0.703125 gal
100 fl oz0.78125 gal
200 fl oz1.5625 gal

Facts about Ounces to Gallons Conversion

  • In every US gallon, there are 128 fluid ounces.
  • A US customary fluid ounce is larger than the imperial fluid ounce.
  • 1 imperial ounce $= 28.4130$ ml 
    1 US ounce $= 29.5735$ ml

Conclusion

In this article, we have learned about conversion from ounces to gallons, the formula, and the steps for conversion. Let’s solve some examples and practice problems to understand the concept better.

Solved Examples on Ounces to Gallons Conversion

1. Convert 64 ounces to gallons. 

Solution: 

1 US gallon $= 128$ US fluid oz

Using ounces to gallons formula,

Gallons $=$ fluid ounces $128 = 64  \div 128 = 0.5$ gallons                                                                                  

Gallons $= 0.0078125 \times $fluid ounce 

64 ounces $= 0.0078125\times 64$

64 ounces $= 0.5$ gallons

2. Convert 128 ounces to gallons. 

Solution: 

1 US gallon $= 128$ US fluid oz

Gallons $=$ fluid ounces $\div 128$

             $= 128  \div 128$

             $=  1$ gallon                                             

3. John has 256 fluid ounces of juice. How many gallons of juice does John have? 

Solution: 

128 US fluid ounces make one gallon.

Thus, 256 fluid ounces $= 2$ gallons

Therefore, John has 2 gallons of juice.

4. Mary wants to store 1152 ounces of oil in separate cans of 1 gallon capacity each. How many such cans does she need to buy?

Solution: 

Mary bought 1152 ounces of oil.

She needs to know how many 1 gallon cans she needs to store the oil.

Using ounces to gallons formula,

Gallons$ = $Fluid ounces$ \div 128$

Thus, 1152 ounces $= 1152 \div 128 = 9$ gallons

Therefore, Mary needs to buy 9 cans to store the oil.

5. Jane uses 256 fluid ounces of water for cooking and 1280 fluid ounces for other purposes. Find out the total usage of water in gallons.

Solution: 

Usage of water for cooking $= 256$ fluid ounces

Usage of water for other purposes $= 1280$ fluid ounces

To find: Total use of water in gallons

Total usage of water $= 256 + 1280 = 1536$ fluid ounces

Using fluid ounces to gallons formula,

Gallons $=$  Fluid ounces $\div 128$

$= 1536 \div 128$

$= 12$

Therefore, the total usage of water is 12 gallons.

Practice Problems on Ounces to Gallons Conversion

Convert Ounces to Gallons (oz to gal): Chart, Formula, Steps, FAQs

Attend this quiz & Test your knowledge.

1

1 US fluid ounce = _________ gallon.

0.0078125
0.00625
0.078125
0.0625
CorrectIncorrect
Correct answer is: 0.0078125
1 US fluid ounce $= 0.0078125$ gallon.
2

1 US gallon = ________ US fluid oz

32
64
128
None of these
CorrectIncorrect
Correct answer is: 128
1 US gallon $= 128$ US fluid oz
3

If you have a $\frac{1}{2}$ gallon of water, how many ounces of water do you have?

32 fl oz
64 fl oz
128 fl oz
2 fl oz
CorrectIncorrect
Correct answer is: 64 fl oz
1 US gallon $= 128$ US fluid oz
$\frac{1}{2}$ gallons $= 128 \div 2 = 64$ fluid ounces.
4

The formula to convert ounces to gallons can be given as ___________.

Gallons $=$ fluid ounce $\times 64$
Gallons $=$ fluid ounces $\div 128$
Gallons $=$ fluid ounces $\div 0.0078125$
Gallons $=$ fluid ounces $ \times 128$
CorrectIncorrect
Correct answer is: Gallons $=$ fluid ounces $\div 128$
Gallons $= 0.0078125$ fluid ounce
Gallons $=$ fluid ounces $\div 128$

Frequently Asked Questions about Ounces to Gallons Conversion

Yes, 128 ounces make 1 gallon, so they are the same.

The imperial gallon is a unit of volume in the imperial system of units, where the US gallon is used exclusively in the United States.

1 US liquid gallon $= 0.832674$ imperial gallon.

1 Imperial fluid ounce $= 28.4130625$ milliliters and the US fluid ounce $= 29.5735295625$ milliliters. The US fluid ounce is about a milliliter larger than an Imperial fluid ounce.

One liquid measuring cup equals 8 fluid ounces, so there are sixteen cups in a gallon.

A fluid ounce (abbreviated as fl oz) is used to measure fluids while an ounce (abbreviated as oz) is for dry measurements.

128 ounces make 1 gallon.