Cubic Millimeters to US Fluid Ounces (mm³ to fl oz)

1 cubic millimeter equals 0.0000338140227 US fluid ounces (rounded).

1 cubic millimeter = 0.0000338140227 US fluid ounces

How to convert cubic millimeters to US fluid ounces

To convert cubic millimeters to US fluid ounces, multiply the number of cubic millimeters by 0.0000338140227. The factor is rounded to 10 significant digits. To go the other way, multiply US fluid ounces by 29,573.52956 (rounded).

US fluid ounces = cubic millimeters × 0.0000338140227

Example: 10 cubic millimeters = 0.000338140227 US fluid ounces.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

Cubic Millimeter (mm³)

Metric (SI)Current unit

One thousandth of a milliliter. Used for tiny volumes.

Geometry supplies the name: a cubic millimeter is the volume of a cube whose edges are each one millimeter long, equal to 10 to the minus 9 cubic meters. Because 1,000 of them fill one cubic centimeter, it is one thousandth of a milliliter, and it is the smallest volume that is commonly written as a cube of length rather than with a liter prefix.

Its tidy equality with the microliter rests on a decision taken in 1964, when the 12th General Conference on Weights and Measures went back to the original definition of the liter as exactly one cubic decimeter. From 1901 until then the liter had been tied to the space taken by a kilogram of water, which made it about 1.000028 cubic decimeters, so volumes in cubic millimeters and microliters differed very slightly. Today 1 mm3 equals 1 microliter exactly, and the figure used here, 0.000001 liter, follows directly from that.

1 cubic millimeter = 0.000001 liters (exactly).

Sources: Wikipedia: Cubic metre; Wikipedia: Litre

US Fluid Ounce (fl oz)

US customaryCurrent unit

One 128th of a US gallon, 29.5735 mL. Not the same as the weight ounce, and about 4% larger than the imperial fluid ounce.

Fluid ounce began as an attempt to link volume to weight: the volume occupied by one ounce of some substance, such as wine in England or water in Scotland. Definitions varied by region and by liquid. When Britain defined its imperial gallon in 1824 as the space of ten pounds of water, the imperial fluid ounce came out so that an ounce of water weighs about one avoirdupois ounce. The US fluid ounce followed a different path and comes from the older wine gallon.

The US fluid ounce is exactly 1/128 of a US gallon, 29.5735295625 milliliters, about 4 percent bigger than the imperial one at 28.4130625 milliliters. American nutrition labels use yet another figure, treating one fluid ounce as 30 milliliters, a convenient rounding for serving sizes. The name is a trap, because a fluid ounce measures space while a weight ounce measures mass. A US fluid ounce of water weighs a bit more than an ounce of weight, while a fluid ounce of honey weighs considerably more.

1 US fluid ounce = 0.02957352956 liters (approximately).

Sources: Wikipedia: Fluid ounce; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures

Related conversions

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