What is US fluid ounce?
A US fluid ounce is a volume unit equal to approximately 29.57 millilitres. It is used in the United States for beverage servings, cooking measurements, and product labelling.
Real-world uses
US fluid ounces are used for beverage labelling (a standard can of soda is 12 fl oz), cooking measurements, and cosmetics packaging in the United States. Cocktail recipes and bartending rely heavily on fluid ounce measurements (a standard shot is 1.5 fl oz).
History
The US fluid ounce derives from the English wine gallon tradition. When the US and UK diverged in measurement standards in the 19th century, their fluid ounces ended up slightly different. The US fluid ounce is defined as 1/128 of a US gallon.
Common mistakes
Confusing US fluid ounces with Imperial fluid ounces—they differ by about 4% (US: 29.57 mL, Imperial: 28.41 mL). Also, confusing fluid ounces (volume) with avoirdupois ounces (weight), which are completely different measurements.
What is Imperial gallon?
An Imperial gallon is a volume unit used in the United Kingdom equal to approximately 4.546 litres. It is larger than the US gallon and is commonly referenced for fuel efficiency (miles per gallon) in the UK.
Real-world uses
Imperial gallons are used in the United Kingdom, Canada (for some purposes), and several Caribbean countries. British fuel economy was historically quoted in miles per Imperial gallon. Older Commonwealth-era recipes and industrial specifications may reference Imperial gallons.
History
The Imperial gallon was established by the British Weights and Measures Act of 1824 as the volume occupied by 10 pounds of water at 62°F (≈ 17°C). It replaced several older gallon definitions including the wine gallon (retained by the US) and the ale gallon.
Common mistakes
Assuming the Imperial gallon equals the US gallon. The Imperial gallon is about 4.546 litres versus 3.785 litres for the US gallon. Converting mpg figures between the two systems without adjusting for gallon size gives misleading results.
When is this conversion used?
Converting US fluid ounce to Imperial gallon is useful in the volume domain when comparing values across different measurement standards or applying formulas that require a specific unit.
Worked examples
1 US fluid ounce = 0.00650527 Imperial gallon
1 Imperial gallon = 4.54609 litre
How to convert US fluid ounce to Imperial gallon
To convert US fluid ounce to Imperial gallon, multiply the value by 0.00650527.
To convert Imperial gallon back to US fluid ounce, multiply by 153.72159046.
Measurement standards
The cubic metre is the SI derived unit of volume. The litre, equal to exactly one cubic decimetre (0.001 m³), is accepted by the BIPM for use alongside SI units. Both the lowercase "l" and uppercase "L" are approved symbols for the litre.
Did you know?
An Olympic swimming pool holds 2,500 cubic metres of water — about 2.5 million litres. The Amazon River discharges roughly 209,000 cubic metres per second, enough to fill 84 Olympic pools every single second.
Quick reference: US fluid ounce to Imperial gallon
| US fluid ounce | Imperial gallon |
|---|---|
| 0.1 | 0.00065053 |
| 0.5 | 0.00325263 |
| 1 | 0.00650527 |
| 2 | 0.01301053 |
| 5 | 0.03252634 |
| 10 | 0.06505267 |
| 25 | 0.16263168 |
| 50 | 0.32526335 |
| 100 | 0.65052671 |
| 250 | 1.62631677 |
| 500 | 3.25263353 |
| 1,000 | 6.50526707 |
Common values
| US fluid ounce | Imperial gallon | |
|---|---|---|
| A teaspoon | 0.16907011 US fluid ounce | 0.00109985 Imperial gallon |
| A cup of coffee | 8.45350568 US fluid ounce | 0.05499231 Imperial gallon |
| A water bottle | 16.90701135 US fluid ounce | 0.10998462 Imperial gallon |
| A bathtub | 10,144.20681055 US fluid ounce | 65.99077449 Imperial gallon |
| A swimming pool (Olympic) | 84,535,056.7546075 US fluid ounce | 549,923.12074772 Imperial gallon |
Available Volume units
More US fluid ounce conversions
- Convert US fluid ounce to litre
- Convert US fluid ounce to millilitre
- Convert US fluid ounce to US gallon
- Convert US fluid ounce to cubic metre
- Convert US fluid ounce to Imperial gallon
- Convert US fluid ounce to Imperial fluid ounce
- Convert US fluid ounce to teaspoon (metric)
- Convert US fluid ounce to tablespoon (metric)
- Convert US fluid ounce to cubic centimetre