fluid ounce

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a measure of capacity equal to 1/16 (0.0625) pint (29.6 milliliters) in the U.S., and equal to 1/20 (0.05) of an imperial pint (28.4 milliliters) in Great Britain. Abbreviation: fl. oz; Symbol: f
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Origin of fluid ounce

First recorded in 1880–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does fluid ounce mean?

A fluid ounce is a unit used in the measurement of the volume of liquids.

It is commonly abbreviated as fl. oz. (or fl oz), which can mean a singular fluid ounce, or, more commonly, the plural fluid ounces.

An ounce is a unit used in the measurement of weight. (Both ounce and ounces can be abbreviated as oz.) A fluid ounce is used to measure volume (capacity), not weight—specifically, the volume of a fluid (liquid). In everyday conversation, the word ounces is often used instead of saying fluid ounces, as in I just drank 16 ounces of that energy drink. The abbreviation oz. is sometimes used in this way, as in a 20 oz. bottle of water. 

You’ll often see the abbreviation fl. oz. on the labels of containers that contain liquid or some other kind of non-solid, such as a can of soda or a bottle of moisturizer, to indicate how much stuff the container contains. It is also seen in recipes.

Fluid ounces are used in the United States Customary System and the British Imperial System of measurement.

In the Customary System, there are 8 fluid ounces in a cup and 16 fluid ounces in a pint. There are 20 fluid ounces in an Imperial pint.

A fluid ounce is equal to 29.57 milliliters (1 milliliter is equivalent to 0.033815 of a fluid ounce.)

Example: Standard soft drink cans contain 12 fluid ounces, but they also sell 8 oz. cans.

Where does fluid ounce come from?

The first records of the term fluid ounce come from around the 1880s. The word ounce has been abbreviated as oz. since at least the 1500s. The abbreviation oz. comes from a shortening of the Italian word onza, meaning “ounce.”

It’s more common to see the abbreviation fl. oz. than to see the phrase fluid ounces spelled out. That’s because it’s commonly used on product labels to indicate how much the container holds. On many products, it often appears alongside a measurement in milliliters, which is usually abbreviated ml or mL.

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What are some other forms related to fluid ounce?

  • fl. oz. (abbreviation)
  • fl oz (abbreviation without periods)

What are some words that share a root or word element with fluid ounce


What are some words that often get used in discussing fluid ounce?

How is fluid ounce used in real life?

Fluid ounce is commonly abbreviated as fl. oz. on product labels.



Try using fluid ounce!

Is fluid ounce used correctly in the following sentence?

The package only contains 64 fluid ounces of flour and that’s not enough for what I’m baking.

How to use fluid ounce in a sentence

British Dictionary definitions for fluid ounce

fluid ounce

a unit of capacity equal to the volume of one avoirdupois ounce of distilled water at 62°F: there are twenty fluid ounces in an Imperial pint and sixteen in a US pint
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for fluid ounce

fluid ounce

A unit of volume or capacity equal to 8 fluid drams or 29.57 milliliters.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for fluid ounce

fluid ounce

A unit of liquid volume or capacity in the US Customary System equal to 116 of a pint (29.57 milliliters). See Table at measurement.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.