When measuring volume, we often use different units. Two common ones are fluid ounces and cubic inches. Both tell you how much space something takes up, but they measure it differently, hence the need for conversion.
This article explains the relationship between fluid ounces and cubic inches and shows you how to convert from one to the other. This conversion is helpful for cooking, science, engineering, and other applications when you need to know the volume of liquids and other materials.
What’s a fluid ounce, anyway?
A fluid ounce (fl oz) is a measurement of volume in the U.S. system of measurement. One fluid ounce is 1/16 of a U.S. pint and 1/128 of a U.S. liquid gallon.
In metric terms, one fluid ounce equals about 29.5735 milliliters (mL), but it’s generally rounded up to an even 30 mL for nutrition labels.
Fluid ounces have been used as a unit of volume in both the Imperial and U.S. systems for a while, but these days the metric system is also common. As a result, you may see volume in both fluid ounces and milliliters on labels of food and drink.
Defining cubic inches
Okay, so what is a cubic inch, anyway? In short, a cubic inch (in³) is a unit of volume. Think of a cube where each side is 1 inch long. The amount of space that cube occupies is one cubic inch.
To put that in metric terms, one cubic inch is equal to 16.387064 cubic centimeters (cm³) or milliliters (mL). So, a cubic inch is a little more than 16 milliliters.
Cubic inches have been used for a long time in the Imperial and U.S. customary systems of measurement. While the metric system is also common, particularly in scientific contexts, cubic inches are still used every day for certain applications.
How to convert fluid ounces to cubic inches
Here’s the conversion factor:
1 fluid ounce (U.S.) = 1.8046875 cubic inches (in³)
So, to convert fluid ounces to cubic inches, use this formula:
Cubic Inches = Fluid Ounces × 1.8046875
For example, let’s convert 5 fluid ounces to cubic inches:
5 fl oz × 1.8046875 = 9.0234375 in³
Keep in mind that this conversion applies to U.S. fluid ounces. Conversions involving imperial ounces are slightly different.
How to convert cubic inches to fluid ounces
The conversion factor is: 1 cubic inch (in³) = 0.5541125541 fluid ounces (US).
Here’s the formula:
Fluid Ounces = Cubic Inches × 0.5541125541
For example, if you wanted to convert 10 cubic inches to fluid ounces, you’d calculate it like this:
10 in³ × 0.5541125541 = 5.541125541 fl oz
Conversion Tables
Sometimes you just need a quick answer. Conversion tables let you look up common values without doing any math. Here are a few examples:
| Fluid Ounces (fl oz) | Cubic Inches (in³) |
|---|---|
| 1 fl oz | 1.8046875 in³ |
| 2 fl oz | 3.609375 in³ |
| 3 fl oz | 5.4140625 in³ |
| 4 fl oz | 7.21875 in³ |
| Cubic Inches (in³) | Fluid Ounces (fl oz) |
|---|---|
| 1 in³ | 0.5541125541 fl oz |
| 2 in³ | 1.1082251082 fl oz |
| 3 in³ | 1.6623376623 fl oz |
| 4 in³ | 2.2164502164 fl oz |
Key Takeaways
A fluid ounce and a cubic inch are both units of volume, and you can convert between them easily. One fluid ounce is about 1.805 cubic inches.
Knowing how to convert between different units can be useful in many situations. If you ever need to convert fluid ounces to cubic inches, refer back to the conversion factors and tables presented here!