US fluid ounces to US gallons Converter
Convert US fluid ounces (fl oz) to US gallons (gal) instantly, or use the conversion table below to look up common values.
US fluid ounces to US gallons conversion table
| US fluid ounces (fl oz) | US gallons (gal) |
|---|---|
| 1 | 0.007813 |
| 2 | 0.015625 |
| 3 | 0.023437 |
| 4 | 0.03125 |
| 5 | 0.039063 |
| 10 | 0.078125 |
| 25 | 0.195313 |
| 50 | 0.390625 |
| 100 | 0.78125 |
How to convert US fluid ounces to US gallons
1 fl oz equals 0.007813 gal. Use the converter above for any value, or read the table for common conversions.
gal = fl oz × 0.0078125 · fl oz = gal × 128Multiply a us fluid ounces figure by 0.007813 to get us gallons, or divide it by 128 to go the other way.
Worked examples
- 1 fl oz= 0.007813 gal
- 2 fl oz= 0.015625 gal
- 5 fl oz= 0.039063 gal
- 10 fl oz= 0.078125 gal
- 20 fl oz= 0.15625 gal
What these units are
US fluid ounces (fl oz). A US fluid ounce is 29.5735295625 milliliters, one sixteenth of a US pint. It is used for drinks, spirits and recipe measures in the United States.
US gallons (gal). A US gallon is 3.785411784 liters, defined as 231 cubic inches. It is the standard liquid and fuel unit in the United States, and is about 20% smaller than an imperial gallon.
US and imperial units are kept separate because they are genuinely different sizes. Confirm which system a source means before trusting a converted figure.
Converting US fluid ounces to US gallons in practice
Working in us fluid ounces
A US fluid ounce is exactly 29.5735295625 milliliters, one 128th of a US gallon. It measures liquid volume and is not the same as the ounce of mass.
Beverage bottles, cocktail recipes, medicine cups, infant formula and cosmetic containers are labelled in US fluid ounces in the United States, and bar measures follow the same unit.
The US fluid ounce is exactly 1/128 of a US gallon, while the imperial fluid ounce is exactly 28.4130625 milliliters. This site uses the US fluid ounce throughout, and printed results are rounded, so a round trip can change the final digit.
The classic error is reading a fluid ounce as a weight ounce, so a 12-fluid-ounce bottle is not 12 ounces of mass. Using an imperial fluid ounce in a US recipe also differs by about four percent.
The US fluid ounce works with US cups and gallons, while milliliters and liters work with metric measures. A drink recipe that mixes them needs every quantity converted, and the fluid ounce should not be swapped for the ounce of mass.
Reading the result in us gallons
A US gallon is exactly 3.785411784 liters, or 231 cubic inches, and it divides into four quarts, eight pints or 128 US fluid ounces. It is a defined liquid volume and not a unit of mass.
Fuel at filling stations, paint, milk, water and agricultural sprays are sold by the US gallon in the United States and in some export markets. Larger tanks and drums are also rated in gallons.
The site uses the US gallon of exactly 3.785411784 liters; the imperial gallon is exactly 4.54609 liters and is roughly a fifth larger. Display rounding can move the final digit of a gallon to liter conversion taken both ways.
The frequent mistake is applying the imperial gallon to a US figure or the reverse, which misstates fuel or tank volume by around a fifth. A gallon also measures volume, while a gallon of a specific liquid has a mass.
The US gallon belongs with quarts, pints and fluid ounces, while the imperial gallon and the liter sit on other scales. Fuel is sold by the gallon in some markets and by the liter in others, so a consumption figure must be converted first.
Checking a us fluid ounces to us gallons conversion
The metric volume units are a clean decimal chain around the liter, so liters to milliliters is a shift of three places and cubic meters to liters is a shift of three the other way. Those pairs a reader can do without a converter.
Every pair that names a US or imperial liquid unit has to go through the definition first, because three of these units differ from a metric unit by amounts too large to round away: a liter is not a quart, a gallon is 3.785411784 liters in the US system and 4.54609 in the imperial one, and a US fluid ounce is not an imperial fluid ounce.
When checking a volume conversion, convert into liters and out again, or measure the container. The mistake that survives every other check is reading a US measure as the imperial unit of the same name, which changes a recipe, a fuel figure or a tank size by about a fifth.
Tanzania reference points
Real quantities, converted into the units on this page.
The 20-litre bucket or canister used to carry water in Tanzania
20 L = 676.280454 fl oz = 5.283441 gal
WaterAid puts the minimum daily water need per person at 20 litres, so one container is roughly one person's daily requirement.
Source: IPS News — water access in Tanzania, citing WaterAid · verified 2026-09-14
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