Convert US Gallons to Fluid Ounces (US)
Convert US Gallons to Fluid Ounces (US) instantly. 1 US Gallon (gal (US)) equals 128 Fluid Ounces (US) (fl oz).
US Gallons to Fluid Ounces (US) conversion table
| US Gallons (gal (US)) | Fluid Ounces (US) (fl oz) |
|---|---|
| 1 gal (US) | 128 fl oz |
| 2 gal (US) | 256 fl oz |
| 3 gal (US) | 384 fl oz |
| 5 gal (US) | 640 fl oz |
| 10 gal (US) | 1,280 fl oz |
| 20 gal (US) | 2,560 fl oz |
| 50 gal (US) | 6,400 fl oz |
| 100 gal (US) | 12,800 fl oz |
| 500 gal (US) | 64,000 fl oz |
| 1,000 gal (US) | 128,000 fl oz |
1 US Gallon = 128 Fluid Ounces (US) · multiply US Gallons by 128
About converting US Gallons to Fluid Ounces (US)
US Gallons (gal (US)) and Fluid Ounces (US) (fl oz) are both units of volume, so converting between them is a single multiplication: multiply your US Gallons figure by 128. Ten US Gallons comes to 1,280 Fluid Ounces (US), and a hundred works out at 12,800 Fluid Ounces (US).
Rule of thumb: going from US Gallons to Fluid Ounces (US) multiplies, so the figure always grows — one US Gallon is already 128 Fluid Ounces (US). If your answer came out smaller, you have the conversion the wrong way round.
What is an US Gallon?
The US gallon is defined as exactly 231 cubic inches, a figure inherited unchanged from the old English wine gallon. When Britain overhauled its measures in 1824 and adopted a new imperial gallon, the United States simply kept the wine gallon it already had — and that single decision is the root of the entire US-versus-imperial mess that still catches people out today. The US gallon is roughly a fifth smaller than the imperial one, which means American and British fuel-economy figures are not comparable even though both are quoted in miles per gallon.
What is a Fluid Ounce (US)?
A fluid ounce measures volume, not weight, despite sharing a name with the ounce on a kitchen scale — the two are related only loosely, through the weight of water. The US and imperial fluid ounces are different sizes, and counterintuitively the imperial one is the smaller, even though the imperial gallon is the bigger of the two: the imperial gallon divides into 160 fluid ounces, the US gallon into just 128. The gap is small enough to slip past a reader and large enough to matter, which makes it a reliable trap in cocktail recipes and drink can sizes.
To put both in perspective: a typical American milk jug holds one US gallon, while a US shot of spirits is about one and a half fluid ounces.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Fluid Ounces (US) to US Gallons converter, or browse all Volume converters.
Frequently asked questions
How many Fluid Ounces (US) are in one US Gallon?
There are 128 Fluid Ounces (US) in one US Gallon.
How do I convert US Gallons to Fluid Ounces (US)?
Multiply the number of US Gallons by 128. For example, 10 US Gallons = 1,280 Fluid Ounces (US).
What is 100 US Gallons in Fluid Ounces (US)?
100 US Gallons is equal to 12,800 Fluid Ounces (US).
How do I convert Fluid Ounces (US) to US Gallons?
Multiply the Fluid Ounces (US) value by 0.007813 (or divide by 128).
Is this US Gallons to Fluid Ounces (US) conversion exact?
The definition is exact — US Gallons and Fluid Ounces (US) are both fixed against the same base by international agreement — but the decimal shown here is rounded for readability, because the true ratio does not terminate. For engineering or scientific work, carry more decimal places than this page displays.
What is an US Gallon?
The US gallon is defined as exactly 231 cubic inches, a figure inherited unchanged from the old English wine gallon. When Britain overhauled its measures in 1824 and adopted a new imperial gallon, the United States simply kept the wine gallon it already had — and that single decision is the root of the entire US-versus-imperial mess that still catches people out today. The US gallon is roughly a fifth smaller than the imperial one, which means American and British fuel-economy figures are not comparable even though both are quoted in miles per gallon.
What is a Fluid Ounce (US)?
A fluid ounce measures volume, not weight, despite sharing a name with the ounce on a kitchen scale — the two are related only loosely, through the weight of water. The US and imperial fluid ounces are different sizes, and counterintuitively the imperial one is the smaller, even though the imperial gallon is the bigger of the two: the imperial gallon divides into 160 fluid ounces, the US gallon into just 128. The gap is small enough to slip past a reader and large enough to matter, which makes it a reliable trap in cocktail recipes and drink can sizes.