Fluid ounce (fl oz) - Unit Information & Conversion
What is a Fluid ounce?
Definition, origin, usage, and conversion formulas for the fluid ounce.
Definition
The fluid ounce is a unit of volume. The US fluid ounce is defined as 1/128 of a US gallon (approx. 29.57 ml). The Imperial fluid ounce is 1/160 of an Imperial gallon (approx. 28.41 ml).
History
Derived from the ounce unit of weight/mass, adapted to measure the volume of liquids like wine or water.
Common Uses
- Beverages: Measuring alcoholic drinks, soft drinks, and coffee servings.
- Cooking: Recipe measurements for smaller liquid ingredients.
- Medicine: Liquid medication dosages on prescription labels.
- Personal Care: Volumes of cosmetics, perfumes, and essential oils.
- Nutrition Labels: Serving sizes on food and beverage packaging.
Unit FAQs
Is a US fluid ounce the same as a UK fluid ounce?
No, the Imperial (UK) fluid ounce is slightly smaller than the US fluid ounce (approximately 28.41 ml vs 29.57 ml).
Is a fluid ounce the same as a weight ounce?
No, a fluid ounce measures volume (the space something occupies), while a weight ounce (specifically an avoirdupois ounce) measures mass (how much matter it contains). The relationship between the two depends entirely on the density of the substance being measured. For water, 1 US fluid ounce weighs approximately 1.04 avoirdupois ounces.
Fluid ounce Conversion Formulas
To Liter:
To Milliliter:
To Cubic meter:
To Gallon (US):
To Gallon (UK):
To Quart:
To Cup:
To Cup (US):
To Pint (US):
Convert Fluid ounce
Need to convert Fluid ounce to other volume units? Use our conversion tool.