What is Imperial fluid ounce?
An Imperial fluid ounce is a volume unit used in the United Kingdom equal to approximately 28.41 millilitres. It is used in British cooking recipes, beverage servings, and pharmaceutical labelling.
Real-world uses
Imperial fluid ounces are used in the United Kingdom, Canada (in some contexts), and other Commonwealth countries for beverage serving sizes and recipe measurements. A British pint is 20 Imperial fluid ounces, compared to the US pint of 16 US fluid ounces.
History
The Imperial fluid ounce was defined by the British Weights and Measures Act of 1824, which established the Imperial gallon based on the volume of 10 pounds of water at 62°F. One Imperial fluid ounce is 1/160 of that gallon.
Common mistakes
Assuming Imperial and US fluid ounces are the same. An Imperial fluid ounce is about 28.41 mL versus 29.57 mL for the US version. This means an Imperial pint (568 mL) is larger than a US pint (473 mL).
What is millilitre?
A millilitre is a metric unit of volume equal to one thousandth of a litre. It is commonly used in medicine, cooking, laboratory measurements, and the labelling of food and beverage products.
Real-world uses
Millilitres are used for medication dosages (cough syrup, injectable solutions), cooking measurements, cosmetic product volumes, and laboratory reagent quantities. A standard medical syringe is graduated in mL, and espresso shots are typically 25–30 mL.
History
The millilitre emerged naturally from the litre with metric prefix conventions. It became essential in medicine and laboratory science where precise small-volume measurements are critical. In medical contexts, "cc" (cubic centimetre) was long used interchangeably with mL.
Common mistakes
Confusing millilitres with cubic centimetres—they are numerically equal (1 mL = 1 cm³) but conceptually different units. Also, mixing up mL with mg; one is volume, the other is mass.
When is this conversion used?
Converting between Imperial fluid ounce and millilitre is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.
Worked examples
1 Imperial fluid ounce = 28.4130625 millilitre
1 millilitre = 0.001 litre
How to convert Imperial fluid ounce to millilitre
To convert Imperial fluid ounce to millilitre, multiply the value by 28.4130625.
To convert millilitre back to Imperial fluid ounce, multiply by 0.03519508.
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: Imperial fluid ounce to millilitre
| Imperial fluid ounce | millilitre |
|---|---|
| 0.1 | 2.84130625 |
| 0.5 | 14.20653125 |
| 1 | 28.4130625 |
| 2 | 56.826125 |
| 5 | 142.0653125 |
| 10 | 284.130625 |
| 25 | 710.3265625 |
| 50 | 1,420.653125 |
| 100 | 2,841.30625 |
| 250 | 7,103.265625 |
| 500 | 14,206.53125 |
| 1,000 | 28,413.0625 |
Common values
| Imperial fluid ounce | millilitre | |
|---|---|---|
| A teaspoon | 0.1759754 Imperial fluid ounce | 5 millilitre |
| A cup of coffee | 8.79876993 Imperial fluid ounce | 250 millilitre |
| A water bottle | 17.59753986 Imperial fluid ounce | 500 millilitre |
| A bathtub | 10,558.52391836 Imperial fluid ounce | 300,000 millilitre |
| A swimming pool (Olympic) | 87,987,699.31963512 Imperial fluid ounce | 2.500000e+09 millilitre |
Available Volume units
More Imperial fluid ounce conversions
- Convert Imperial fluid ounce to litre
- Convert Imperial fluid ounce to millilitre
- Convert Imperial fluid ounce to US gallon
- Convert Imperial fluid ounce to cubic metre
- Convert Imperial fluid ounce to Imperial gallon
- Convert Imperial fluid ounce to US fluid ounce
- Convert Imperial fluid ounce to teaspoon (metric)
- Convert Imperial fluid ounce to tablespoon (metric)
- Convert Imperial fluid ounce to cubic centimetre