Gallons to Ounces Conversion Calculator and Chart

Gallon is a volume unit that exists in both imperial and US customary systems. Gallon is the largest volume unit in both the US customary and imperial measurement systems. US gallon is equivalent to 8.3389 avoirdupois pounds (3.78 kg) of distilled water at its maximum density or 231 cubic inches and with the barometer at 30 inches.

An imperial gallon, abbreviated “gal”, is officially defined as equal in volume to 10 avoirdupois pounds (4.53 kg) of distilled water weighed at 62 degrees Fahrenheit (16.66 degrees Celsius) with barometer at 30 inches (or equal to 277.421 cubic inches). The imperial gallon is 17% larger than the US gallon.

Fluid ounce, abbreviated as “fl oz”, is an imperial and US customary measurement system volume unit. Fluid ounce is the smallest unit of volume in both the imperial and US customary systems. UK fluid ounce equals to one twentieth of a pint and US fluid ounce equals to one sixteenth of a US pint.

Gallons to ounces conversion has factors are listed below. To find out how many ounces in gallons, multiply by the conversion factors or use the converter.

How to Convert Ounces to Gallons

1 Gallon [Fluid, US] = 128 Ounces [Fluid, US]
1 Gallon [Dry, US] = 148.94684 Ounces [Fluid, US]
1 Gallon [UK] = 160 Ounces [UK]

UK Fluid OuncesUK GallonsUK Fluid OuncesUK GallonsUK Fluid OuncesUK Gallons
0uk fl oz0.00UK gal20uk fl oz0.12UK gal40uk fl oz0.25UK gal
1uk fl oz0.01UK gal21uk fl oz0.13UK gal41uk fl oz0.26UK gal
2uk fl oz0.01UK gal22uk fl oz0.14UK gal42uk fl oz0.26UK gal
3uk fl oz0.02UK gal23uk fl oz0.14UK gal43uk fl oz0.27UK gal
4uk fl oz0.03UK gal24uk fl oz0.15UK gal44uk fl oz0.28UK gal
5uk fl oz0.03UK gal25uk fl oz0.16UK gal45uk fl oz0.28UK gal
6uk fl oz0.04UK gal26uk fl oz0.16UK gal46uk fl oz0.29UK gal
7uk fl oz0.04UK gal27uk fl oz0.17UK gal47uk fl oz0.29UK gal
8uk fl oz0.05UK gal28uk fl oz0.18UK gal48uk fl oz0.30UK gal
9uk fl oz0.06UK gal29uk fl oz0.18UK gal49uk fl oz0.31UK gal
10uk fl oz0.06UK gal30uk fl oz0.19UK gal50uk fl oz0.31UK gal
11uk fl oz0.07UK gal31uk fl oz0.19UK gal51uk fl oz0.32UK gal
12uk fl oz0.08UK gal32uk fl oz0.20UK gal52uk fl oz0.33UK gal
13uk fl oz0.08UK gal33uk fl oz0.21UK gal53uk fl oz0.33UK gal
14uk fl oz0.09UK gal34uk fl oz0.21UK gal54uk fl oz0.34UK gal
15uk fl oz0.09UK gal35uk fl oz0.22UK gal55uk fl oz0.34UK gal
16uk fl oz0.10UK gal36uk fl oz0.23UK gal56uk fl oz0.35UK gal
17uk fl oz0.11UK gal37uk fl oz0.23UK gal57uk fl oz0.36UK gal
18uk fl oz0.11UK gal38uk fl oz0.24UK gal58uk fl oz0.36UK gal
19uk fl oz0.12UK gal39uk fl oz0.24UK gal59uk fl oz0.37UK gal

There are 128 ounces in a gallon, because from gallon to fl. ounce, there are 4 quarts in a gallon, 2 pints in a quart, 2 cups in a pint and 8 fl. ounces in a cup, that makes 4 * 2 * 2 * 8 = 128 fl. ounces in a gallon.

For example, to find out how many ounces of water in a half gallon, multiply the gallon value by the conversion factor, that makes 1/2 gal * 128 = 64 fl. ounces of water in a half gallon.

For US fluid gallons, there are 128 ounces in a gallon, 64 fl. oz in 1/2 gallon, 32 fl. oz in 1/4 gallon, 16 fl. oz in 1/8 gallon, 42.6 fl. oz in 1/3 gallon and 96 fl. oz in 3/4 gallon.

For UK gallons, there are 160 ounces in an imperial gallon, 80 fl. oz in 1/2 gallon, 40 fl. oz in 1/4 gallon, 20 fl. oz in 1/8 gallon, 53.3 fl. oz in 1/3 gallon and 120 fl. oz in 3/4 gallon.