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Convertitive

US gallons to US fluid ounces Converter

1 gal = 128 fl oz

1 US gallon equals 128 US fluid ounces. To convert US gallons to US fluid ounces, multiply the US gallon value by 128. For quick reference: 1 gal = 128 fl oz, 5 gal = 640 fl oz, 10 gal = 1280 fl oz, 100 gal = 12800 fl oz.

128
FormulaUS fluid ounces = US gallons × 128
Quick

How to convert US gallons to US fluid ounces

  1. Take your value

    Start with your value in US gallons.

  2. Multiply by 128

    Multiply the US gallon value by 128. This is the exact conversion factor from US gallons to US fluid ounces.

  3. Read the result

    The product is your value in US fluid ounces. For example, 5 gal × 128 = 640 fl oz.

Conversion formula

The exact factor from US gallons to US fluid ounces is 128.

US fluid ounces = US gallons × 128

US gallons to US fluid ounces conversion table

Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.

Conversion table from US gallons to US fluid ounces
US gallons (gal)US fluid ounces (fl oz)
0.1 gal12.8 fl oz
0.25 gal32 fl oz
0.5 gal64 fl oz
1 gal128 fl oz
1.5 gal192 fl oz
2 gal256 fl oz
2.5 gal320 fl oz
3 gal384 fl oz
4 gal512 fl oz
5 gal640 fl oz
6 gal768 fl oz
7 gal896 fl oz
8 gal1024 fl oz
9 gal1152 fl oz
10 gal1280 fl oz
12 gal1536 fl oz
15 gal1920 fl oz
20 gal2560 fl oz
25 gal3200 fl oz
30 gal3840 fl oz
40 gal5120 fl oz
50 gal6400 fl oz
60 gal7680 fl oz
75 gal9600 fl oz
100 gal12800 fl oz
125 gal16000 fl oz
150 gal19200 fl oz
200 gal25600 fl oz
250 gal32000 fl oz
300 gal38400 fl oz
400 gal51200 fl oz
500 gal64000 fl oz
600 gal76800 fl oz
750 gal96000 fl oz
1000 gal128000 fl oz
1500 gal192000 fl oz
2000 gal256000 fl oz
2500 gal320000 fl oz
3000 gal384000 fl oz
4000 gal512000 fl oz
5000 gal640000 fl oz
7500 gal960000 fl oz
10000 gal1280000 fl oz
15000 gal1920000 fl oz
20000 gal2560000 fl oz
25000 gal3200000 fl oz
30000 gal3840000 fl oz
40000 gal5120000 fl oz
50000 gal6400000 fl oz
100000 gal12800000 fl oz

Real-world reference

A standard US milk jug holds 1 gal. An average car's fuel tank is 12–16 gal. In US fluid ounces, that gives you: 1 gal = 128 fl oz, 10 gal = 1280 fl oz, 100 gal = 12800 fl oz.

Frequently asked questions

How many US fluid ounces are in 1 US gallon?
1 US gallon equals 128 US fluid ounces.
How do I convert US gallons to US fluid ounces?
Multiply the US gallon value by 128. So x gal × 128 = the equivalent in fl oz.
What is 5 US gallons in US fluid ounces?
5 US gallons equals 640 US fluid ounces.
What is 10 US gallons in US fluid ounces?
10 US gallons equals 1280 US fluid ounces.
What is 100 US gallons in US fluid ounces?
100 US gallons equals 12800 US fluid ounces.
How do I convert back from US fluid ounces to US gallons?
Multiply the US fluid ounce value by 0.0078125. For example, 1 fl oz = 0.0078125 gal.
Is the US gallon bigger than the US fluid ounce?
Yes. 1 US gallon is larger than 1 US fluid ounce — specifically 128 times larger.
Are these conversion factors exact?
Yes. The factor of 128 is derived directly from the SI definitions of US gallon and US fluid ounce.

About the US gallon and the US fluid ounce

The US gallon

The US liquid gallon equals exactly 3.785411784 liters, defined as 231 cubic inches. It is the standard fuel and milk unit in the United States. The US gallon is about 16.7% smaller than the UK (imperial) gallon (4.54609 L), so quoting fuel economy as 'mpg' without specifying the gallon can mislead by a wide margin.

The US fluid ounce

The US fluid ounce (fl oz) is a customary unit of volume equal to 1/128 of a US gallon, or about 29.5735 mL. It is the standard unit for liquid serving sizes on US nutrition labels. The US fluid ounce is slightly larger than the UK fluid ounce (28.4131 mL) — confusingly, the opposite direction from the gallons.

Related converters

US fluid ounces to US gallons
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Milliliters to US gallons
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Milliliters to US fluid ounces
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Milliliters to US pints
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Sources