A US fluid ounce is 1/128 of a US gallon.
Fluid ounces to Cubic inches Converter — fl oz to in3
Convert Fluid ounce (fl oz) to Cubic inch (in3) using the exact conversion factor (1 fluid ounce = 1.8046875 cubic inch). See the formula, worked examples, conversion table, history, and common uses.
Fluid ounces to Cubic inches converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
A cubic inch is the volume of a one-inch cube.
Result = input x 2.95735296e-5 / 1.6387064e-5.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Fluid ounces to Cubic inches
Fluid ounce and Cubic inch appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Fluid ounce is most often used for us beverage container sizing (soda, water bottles).
Formula
cubic inches = fluid ounces × 1.8046875
This factor comes from each unit's defined relationship to the category's base unit: 1 fluid ounce equals 0.0000295735295625 base units, and 1 cubic inch equals 0.000016387064 base units, so dividing one by the other gives the direct fluid ounce-to-cubic inch factor of 1.8046875.
Simple example
1 fl oz × 1.8046875 = 1.8046875 in3
1 fluid ounce = 1.8046875 cubic inches.
Real-world example
10 fl oz × 1.8046875 = 18.046875 in3
10 fluid ounces = 18.046875 cubic inches.
Conversion table
| Fluid ounce (fl oz) | Cubic inch (in3) |
|---|---|
| 1 fl oz | 1.8046875 in3 |
| 5 fl oz | 9.0234375 in3 |
| 10 fl oz | 18.046875 in3 |
| 25 fl oz | 45.1171875 in3 |
| 50 fl oz | 90.234375 in3 |
| 100 fl oz | 180.46875 in3 |
Reverse conversion: Cubic inch to Fluid ounce
1.8046875 in3 × 0.5541125541 = 1 fl oz
1.8046875 cubic inches = 1 fluid ounces.
fluid ounces = cubic inches × 0.554112554113
For a page dedicated to this direction, see Cubic inch to Fluid ounce.
Understanding the Fluid ounce
Fluid ounce (fl oz) measures volume. The US fluid ounce is 1/128 of a US gallon: exactly 29.5735295625 milliliters. It is classified as a US customary unit.
Where it's used: United States (beverage, nutrition labeling)
Uses of the Fluid ounce today
- US beverage container sizing (soda, water bottles)
- US nutrition and medication dosing labels
History of the Fluid ounce
The US fluid ounce follows from the same English wine-gallon system as the rest of the US liquid volume units, defined as a consistent fraction of the gallon.
Historical origin. Fluid ounce was not the invention of a single named person; it developed through the process described above.
Understanding the Cubic inch (in3)
A cubic inch is the volume of a one-inch cube.
Fluid ounce — sources
- NIST Handbook 44, Appendix C — General tables of units including the US fluid ounce definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many cubic inches are in 1 fluid ounce?
1 fluid ounce equals 1.8046875 cubic inches, using the exact defined conversion factor rather than an estimate.
How do I convert fluid ounce to cubic inch?
Multiply the fluid ounce value by 1.8046875. The converter above does this instantly to whatever precision you set.
How do I convert cubic inch back to fluid ounce?
Use the reverse factor: 1 cubic inch equals 0.5541125541 fluid ounces. You can also use the swap control in the converter above to flip the direction instantly.
What is a fluid ounce?
Fluid ounce (fl oz) measures volume. The US fluid ounce is 1/128 of a US gallon: exactly 29.5735295625 milliliters. It is classified as a US customary unit.
What is a cubic inch?
Cubic inch (in3) is a unit of volume.
Is the fluid ounce to cubic inch conversion exact?
Yes. The US fluid ounce is 1/128 of a US gallon: exactly 29.5735295625 milliliters. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the fluid ounce still used today?
United States (beverage, nutrition labeling)