US Gallons to US Fluid Ounces Converter
One US Gallon equals 128 US Fluid Ounces (1 gal = 128 fl-oz). Multiply a US Gallon value by 128 to get the equivalent in US Fluid Ounces. Enter a value above to calculate the result. You can also use the formula and reference table below.
Formula
fl-oz = gal × 128
Multiply the US Gallon value by 128 to get the equivalent value in US Fluid Ounces.
Example Conversions
1 US Gallon (gal)
128 US Fluid Ounce (fl-oz)
5 US Gallon (gal)
640 US Fluid Ounce (fl-oz)
10 US Gallon (gal)
1280 US Fluid Ounce (fl-oz)
25 US Gallon (gal)
3200 US Fluid Ounce (fl-oz)
100 US Gallon (gal)
12800 US Fluid Ounce (fl-oz)
Conversion Table
| US Gallon (gal) | US Fluid Ounce (fl-oz) |
|---|---|
| 0.1 | 12.8 |
| 0.5 | 64 |
| 1 | 128 |
| 2 | 256 |
| 5 | 640 |
| 10 | 1280 |
| 25 | 3200 |
| 50 | 6400 |
| 100 | 12800 |
| 250 | 32000 |
| 500 | 64000 |
| 1000 | 128000 |
How to Convert Manually
Use these steps to convert US Gallon values to US Fluid Ounce without the calculator.
- Write down the value in US Gallon (gal) that you want to convert.
- Multiply that value by 128.
- For example, 10 US Gallons × 128 = 1280 US Fluid Ounces.
- Label the result as US Fluid Ounce (fl-oz).
Relative Size Comparison
This chart shows the visual difference in size between exactly one US Gallon and one US Fluid Ounce.
About US Gallon and US Fluid Ounce
The US gallon is defined as 231 cubic inches, exactly 3.785411784 liters. US fuel prices, milk jugs, and paint cans are all per-gallon quantities. The US fluid ounce is about 29.574 milliliters, one eighth of a US cup. Beverage cans, cosmetics, and baby formula in the US are labeled in fluid ounces. One US Gallon equals 128 US Fluid Ounces (1 gal = 128 fl-oz). US Gallon is used in US fuel prices and in US milk and beverage containers. US Fluid Ounce is used in US beverage can and bottle sizes.
Precision and Rounding:US and imperial volume units share names but differ in size (an imperial gallon is about 20% larger than a US gallon), so confirm which system a figure uses before converting. Kitchen work tolerates rounding to the nearest milliliter or quarter-teaspoon; fuel, chemistry, and brewing need three or more decimal places.
Conversion factors per NIST Special Publication 811 and the BIPM SI Brochure (9th edition) (reference).
Worked Example
15US Gallons equals1920US Fluid Ounces.
15 gal × 128 = 1920 fl-oz
FAQ
How do I convert US Gallon to US Fluid Ounce?
Multiply the US Gallon value by 128 to get the equivalent value in US Fluid Ounces.
What is the formula for US Gallon to US Fluid Ounce?
The formula is fl-oz = gal × 128.
How many US Fluid Ounces are in 1 US Gallon?
1 US Gallon equals 128 US Fluid Ounces.
Can I convert US Fluid Ounce back to US Gallon?
Yes. 1 US Fluid Ounce equals 0.0078125 US Gallons, and the related converter can reverse the calculation.
What are common names for US Gallon and US Fluid Ounce?
US Gallon is shown as gal and may also be searched as gallons, us gallons. US Fluid Ounce is shown as fl-oz and may also be searched as fluid ounces, fl oz, us fl oz.
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