US Fluid Ounces to US Gallons (fl oz to gal)
1 US fluid ounce equals 0.0078125 US gallons exactly.
How to convert US fluid ounces to US gallons
To convert US fluid ounces to US gallons, multiply the number of US fluid ounces by 0.0078125. This factor is exact. To go the other way, multiply US gallons by 128.
US gallons = US fluid ounces × 0.0078125
Example: 10 US fluid ounces = 0.078125 US gallons.
Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.
About these units
US Fluid Ounce (fl oz)
One 128th of a US gallon, 29.5735 mL. Not the same as the weight ounce, and about 4% larger than the imperial fluid ounce.
Fluid ounce began as an attempt to link volume to weight: the volume occupied by one ounce of some substance, such as wine in England or water in Scotland. Definitions varied by region and by liquid. When Britain defined its imperial gallon in 1824 as the space of ten pounds of water, the imperial fluid ounce came out so that an ounce of water weighs about one avoirdupois ounce. The US fluid ounce followed a different path and comes from the older wine gallon.
The US fluid ounce is exactly 1/128 of a US gallon, 29.5735295625 milliliters, about 4 percent bigger than the imperial one at 28.4130625 milliliters. American nutrition labels use yet another figure, treating one fluid ounce as 30 milliliters, a convenient rounding for serving sizes. The name is a trap, because a fluid ounce measures space while a weight ounce measures mass. A US fluid ounce of water weighs a bit more than an ounce of weight, while a fluid ounce of honey weighs considerably more.
1 US fluid ounce = 0.02957352956 liters (approximately).
Sources: Wikipedia: Fluid ounce; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures
US Gallon (gal)
Exactly 231 cubic inches or 3.785411784 liters (128 US fluid ounces). About 17% smaller than the imperial gallon.
The US gallon is a survivor of English wine trade. Around 1706, a statute in Queen Anne's reign fixed the wine gallon at exactly 231 cubic inches, settling confusion among the competing gallons for wine, ale and corn. British colonies in North America used that wine gallon, and in 1824 Britain replaced all its gallons with a new imperial one while the United States kept the old measure. It was adopted as the legal US standard in 1836 and is still defined as exactly 231 cubic inches, or 3.785411784 liters.
That makes the US gallon about 17 percent smaller than the imperial gallon, a difference that explains why American and British fuel-economy figures cannot be compared directly. Everyday uses are milk jugs, paint cans and gasoline pumps. One gallon divides evenly into four quarts, eight pints, sixteen cups and 128 fluid ounces. A gallon of water weighs a little over 8 pounds, an easy figure to remember when loading a car with water jugs.
1 US gallon = 3.785411784 liters (exactly).
Sources: Wikipedia: Gallon; NIST SP 811, Appendix B.8: conversion factors for volume
Related conversions
- US gallons to US fluid ounces (reverse)
- US fluid ounces to liters
- US fluid ounces to milliliters
- US fluid ounces to US cups
- US fluid ounces to cubic meters
- US fluid ounces to cubic centimeters
- US fluid ounces to US quarts
- US fluid ounces to US pints
- US fluid ounces to US tablespoons
- US fluid ounces to US teaspoons
- US fluid ounces to metric cups
- US fluid ounces to metric tablespoons
- US fluid ounces to metric teaspoons
- Liters to US gallons
- Milliliters to US gallons
- US cups to US gallons
- Cubic meters to US gallons
- Cubic centimeters to US gallons
- US quarts to US gallons
- US pints to US gallons
- US tablespoons to US gallons
- US teaspoons to US gallons
- Metric cups to US gallons
- Metric tablespoons to US gallons
- Metric teaspoons to US gallons
See all volume units.