How many cubic inches are in a fluid ounce?

For US fluid ounces: exactly 231/128 ≈ 1.8046875 cubic inches per fl oz (derived from the US gallon definition of 231 in³ = 128 fl oz). For UK fluid ounces: approximately 1.7338715 cubic inches per fl oz.

What is the formula for fluid ounces to cubic inches?

US: in³ = fl oz × (231 ÷ 128). UK: in³ = fl oz × 1.7338715. Reverse: US fl oz = in³ × (128 ÷ 231); UK fl oz = in³ ÷ 1.7338715.

What is the difference between US and UK fluid ounces?

A US fluid ounce is exactly 29.5735 mL, while a UK (imperial) fluid ounce is 28.4131 mL — about 4% smaller. Always confirm which system is intended before converting.

Can I type a decimal value?

Yes. The converter accepts any non-negative decimal in either field and rounds results to six significant figures.

Why do fluid ounces and cubic inches coexist in US measurements?

Fluid ounces are a volume unit defined relative to the gallon (128 fl oz = 1 US gal = 231 in³), while cubic inches are the direct geometric unit. Both appear in engineering, cooking, and product specs, so converting between them is a common practical need.

Fluid Ounces to Cubic Inches Converter

Name: Fluid Ounces to Cubic Inches Converter
Availability: InStock
Author: Nham Vu

Convert US fluid ounces to cubic inches (and back) instantly, with a volume reference table for common household and industrial containers.

Volume Converter

Unit System

Fluid Ounces (US fl oz)

Cubic Inches (in³)

Converted Result

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Enter a value to convert

Common Volume Reference

Container	US fl oz	in³

Summary

Convert US fluid ounces to cubic inches (and back) instantly, with a volume reference table for common household and industrial containers.

How it works

Enter a value in the fluid ounces field or the cubic inches field.
Select US fl oz or UK fl oz depending on your system.
The opposite field updates instantly as you type.
Click "Swap" to reverse direction, or "Clear" to reset both fields.
Scroll down to the reference table to see common container volumes.

Use cases

Convert engine displacement or pump capacity from fl oz specs to cubic inches.
Scale cooking or beverage recipes that mix US and metric units.
Verify container fill volumes for packaging or product design.
Cross-check fluid capacity listed in automotive or marine parts catalogs.
Compare laboratory glassware sizes when setting up experiments.
Quickly sanity-check unit conversions on homework or exam problems.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu