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Math help from the Learning Centre

This guide provides useful resources for a wide variety of math topics. It is targeted at students enrolled in a math course or any other Centennial course that requires math knowledge and skills.

Fluid Ounce vs Ounce

What is the difference between a Fluid Ounce and an Ounce?

Fluid ounces (fl oz.) are used to measure fluids/liquids while an ounces (oz.) are used for dry measurements. Thus, fluid ounces are used to measure volume and ounces are used to measure weight.


Therefore, you need to know what it is you are measuring and not the object you are measuring from. For example, if you are using a cup to measure, you used fluid ounces if the cup contains milk. Whereas, if the cup contains sugar, you use ounces.

Conversions with Fluid Ounces

Volume Measure Equivalent in Fluid Ounces
1 tablespoon \(\frac{1}{2}\) fluid ounce
1 cup 8 fluid ounces
1 pint 16 fluid ounces
1 quart 32 fluid ounces
1 gallon 128 fluid ounces

Example 1

Honey is poured into a jug that is equivalent to 3.5 quarts. How many fluid ounces are in 3.5 cups?


First, honey is a fluid/liquid, so fluid ounces are the correct measurement and not ounces.

\[ 3.5\, quarts \times \frac{32\, fl. oz.}{1\, quarts} = 112\, quarts\]

Example 2
We have 21 fluid ounces of juice. How many cups of juice do we have?


We know that 1 cup is equivalent to 8 fluid ounces. Using this, we get

\[21\, fl. oz. \times \frac{1\, cup}{8\, fl. oz.} = \frac{21}{8}\, cups = 2.625 \,cups\]

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Designed by Matthew Cheung. This work is licensed under a Creative Commons Attribution 4.0 International License.
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