How many ounces in a gallon? One gallon has 128 -ounces. One gallon of water equals 160 fluid ounces in metric systems. How many ounces in a half gallon? The answer is 64 fluid ounces per half gallon. The full gallon contains 128 fluid ounces, while the half gallon contains 64 fluid ounces.

U.S and U.K Imperial Measurement Systems

The US system (a variant of the Imperial system) and the UK Imperial. These systems were most popular due to the advancement of technology and growth in population.

The implementation of the metric system was late. Today, the metric system is used in most countries. Because the world is now a global village, people use standardize units for business to avoid miscommunications and obstacles.

We still see the British and American systems being used in certain cases. It is a tradition that they have inherited and it is difficult for them to switch to the new metric system.


1 US fl gal = 3.785 liters

1 Liters = 33.814 US fl oz

1 fl Gal = 3.785 x 33.814 = 128 oz


1 imperial fl gallon = 4.54609 liters

1 Liters = 35.1951 UK fl o

1 fluid Gallon = 4.54609 x 35.1951 = 160 ounces

Ounces to Gallon Conversion

Before standardization of these units, the conversion from an ounce to a gallon was subject to much debate. But it is no big deal now. Two different measurement systems are currently in use around the world. The first is the imperial British measurement system, while the second is the United States measurement system. Each one has a slight difference, which we have discussed previously.

Fluid Ounce to Gallon Table

The table below shows the exact measurements of U.S. gallon and Imperial Gallon in fluid.

Fluid ounce U.S Liquid Gallon Imperial Gallon
1 0.00750594 0.00625
2 0.0150119 0.0125
3 0.0225178 0.01875
4 0.0300237 0.025
5 0.0375297 0.03125
6 0.0450356 0.0375
7 0.0525416 0.04375
8 0.0600475 0.05
9 0.0675534 0.05625
10 0.0750594 0.0625
20 0.150119 0.125
30 0.225178 0.1875
40 0.300237 0.25
50 0.375297 0.3125
60 0.450356 0.375
70 0.525416 0.4375
80 0.600475 0.5
90 0.675534 0.5625
100 0.750594 0.625

How Many Ounces are Required to Drink a Gallon of Water Per Day?

The Mayo Clinic recommends an average person should drink 8 standard glasses per day. This is in line with the body’s requirements. A gallon contains 160 fl. ounces of water and 8 fl. ounces.

How Many 16.9 oz in a Gallon?

Well it’s a complicated question, but the answer is simple. There are 7.57 bottles of 16.9 US fluid-ounces water, which is exactly equivalent to one US gallon. The U.S Measurement System is different from both the Imperial Measurement System or the international Metric Measurement Systems.

How many 16.9 oz in a gallon? The answer is the same. A gallon is 7.57 water bottles.

How many ounces in a half gallon of water?

It is easy to find out how many ounces in a half gallon of water. We know there are in half a gallon of water contains 64 fl. oz.

How many oz in a water bottle? The answer is: 128 fluid ounces = 1 gallon of water.

160 Imperial liquid ounces is equal to 1 Imperial gallon. The Imperial gallon is larger than the U.S. gallon.


It’s clear now that How many ounces in a gallon and How many ounces in a half gallon.

The Exact Answer is:

One gallon of water equals 128 U.S fluid ounces, while a half gallon contains 64 U.S fluid ounces.

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