Fluid Ounces to Milligrams Converter

How to Convert Fluid Ounces to Milligrams

Since fluid ounces are a unit of volume and milligrams are a unit of mass, which are different physical quantities, we need to know one more physical quantity of the ingredient or substance to convert between them. In this case, we need to account for the density of the substance whenever we do a conversion.

Therefore, to convert between fluid ounces and milligrams of an ingredient or substance, we must either multiply or divide by its density, depending on which direction we are performing the conversion.

Fluid Ounces to Milligrams Formula

To convert a measurement in fluid ounces to milligrams, multiply the volume by the density of the ingredient or material. Note that in order for this to work, the density must be in milligrams per fluid ounce (mg/fl oz).

If the density is given in grams per milliliter (g/mL), then first multiply the density by 29,573.53 to convert to mg/fl oz.

For a density given in g/mL, you can use this simple formula to convert:

milligrams = fluid ounces × 29,573.53 × density

Thus, the weight in milligrams is equal to the volume in fluid ounces multiplied by 29,573.53 times the density (in g/mL) of the ingredient, substance, or material.

For example, here's how to convert 5 fluid ounces to milligrams for an ingredient with a density of 0.7 g/mL.

milligrams = 5 fl oz × 29,573.53 × 0.7 g/mL = 103,507.353 mg

When to Convert Fluid Ounces to Milligrams

Fluid ounces and milligrams are both commonly used to measure cooking ingredients.

For cooking applications, most chefs suggest measuring dry ingredients by weight rather than volume to improve accuracy in the measurements.^[1] The density of dry ingredients can vary for a variety of reasons, such as compaction and clumping.

The best way to ensure an accurate conversion is to use a scale. When a scale is not available, a calculator like the one above is a good way to estimate the volume to weight conversion.

Another useful application of weight and volume conversions is chemistry. When performing chemical reactions by combining separate chemicals to produce a new chemical, one must know the exact amount of each chemical to add in order to maximize the yield of the reaction.

It is common to mix powdered chemicals with liquid, or aqueous, chemicals, and this is where it becomes very useful to convert between weights and volumes.^[2]

Keep reading to learn more about each unit of measure.

How Many Milligrams Are in a Fluid Ounce?

The actual weight of a fluid ounce will vary depending on the density of the material. The table below shows how many milligrams of various wet and dry ingredients are in a fluid ounce.

Fluid ounce measurements converted to milligrams for commonly used cooking and baking ingredients.
Volume in Fluid Ounces:	Weight in Milligrams of:
Volume in Fluid Ounces:	Water	Milk	Cooking Oil	All Purpose Flour	Granulated Sugar
0.01 fl oz	295.74 mg	304.61 mg	260.25 mg	156.44 mg	250 mg
0.02 fl oz	591.47 mg	609.21 mg	520.49 mg	312.89 mg	500 mg
0.03 fl oz	887.21 mg	913.82 mg	780.74 mg	469.33 mg	750 mg
0.04 fl oz	1,183 mg	1,218 mg	1,041 mg	625.78 mg	1,000 mg
0.05 fl oz	1,479 mg	1,523 mg	1,301 mg	782.22 mg	1,250 mg
0.06 fl oz	1,774 mg	1,828 mg	1,561 mg	938.66 mg	1,500 mg
0.07 fl oz	2,070 mg	2,132 mg	1,822 mg	1,095 mg	1,750 mg
0.08 fl oz	2,366 mg	2,437 mg	2,082 mg	1,252 mg	2,000 mg
0.09 fl oz	2,662 mg	2,741 mg	2,342 mg	1,408 mg	2,250 mg
0.1 fl oz	2,957 mg	3,046 mg	2,602 mg	1,564 mg	2,500 mg
0.11 fl oz	3,253 mg	3,351 mg	2,863 mg	1,721 mg	2,750 mg
0.12 fl oz	3,549 mg	3,655 mg	3,123 mg	1,877 mg	3,000 mg
0.13 fl oz	3,845 mg	3,960 mg	3,383 mg	2,034 mg	3,250 mg
0.14 fl oz	4,140 mg	4,265 mg	3,643 mg	2,190 mg	3,500 mg
0.15 fl oz	4,436 mg	4,569 mg	3,904 mg	2,347 mg	3,750 mg
0.16 fl oz	4,732 mg	4,874 mg	4,164 mg	2,503 mg	4,000 mg
0.17 fl oz	5,028 mg	5,178 mg	4,424 mg	2,660 mg	4,250 mg
0.18 fl oz	5,323 mg	5,483 mg	4,684 mg	2,816 mg	4,500 mg
0.19 fl oz	5,619 mg	5,788 mg	4,945 mg	2,972 mg	4,750 mg
0.2 fl oz	5,915 mg	6,092 mg	5,205 mg	3,129 mg	5,000 mg
0.21 fl oz	6,210 mg	6,397 mg	5,465 mg	3,285 mg	5,250 mg
0.22 fl oz	6,506 mg	6,701 mg	5,725 mg	3,442 mg	5,500 mg
0.23 fl oz	6,802 mg	7,006 mg	5,986 mg	3,598 mg	5,750 mg
0.24 fl oz	7,098 mg	7,311 mg	6,246 mg	3,755 mg	6,000 mg
0.25 fl oz	7,393 mg	7,615 mg	6,506 mg	3,911 mg	6,250 mg
0.26 fl oz	7,689 mg	7,920 mg	6,766 mg	4,068 mg	6,500 mg
0.27 fl oz	7,985 mg	8,224 mg	7,027 mg	4,224 mg	6,750 mg
0.28 fl oz	8,281 mg	8,529 mg	7,287 mg	4,380 mg	7,000 mg
0.29 fl oz	8,576 mg	8,834 mg	7,547 mg	4,537 mg	7,250 mg
0.3 fl oz	8,872 mg	9,138 mg	7,807 mg	4,693 mg	7,500 mg
0.31 fl oz	9,168 mg	9,443 mg	8,068 mg	4,850 mg	7,750 mg
0.32 fl oz	9,464 mg	9,747 mg	8,328 mg	5,006 mg	8,000 mg
0.33 fl oz	9,759 mg	10,052 mg	8,588 mg	5,163 mg	8,250 mg
0.34 fl oz	10,055 mg	10,357 mg	8,848 mg	5,319 mg	8,500 mg
0.35 fl oz	10,351 mg	10,661 mg	9,109 mg	5,476 mg	8,750 mg
0.36 fl oz	10,646 mg	10,966 mg	9,369 mg	5,632 mg	9,000 mg
0.37 fl oz	10,942 mg	11,270 mg	9,629 mg	5,788 mg	9,250 mg
0.38 fl oz	11,238 mg	11,575 mg	9,889 mg	5,945 mg	9,500 mg
0.39 fl oz	11,534 mg	11,880 mg	10,150 mg	6,101 mg	9,750 mg
0.4 fl oz	11,829 mg	12,184 mg	10,410 mg	6,258 mg	10,000 mg

What Is a Fluid Ounce?

The US fluid ounce is a unit of volume equal to 1/16 of a pint or 1/8 of a cup. The fluid ounce is sometimes referred to as just an "ounce" but should not be confused with the unit of weight. One fluid ounce is equal to approximately 29.5735 milliliters, but in nutrition labeling, one fluid ounce is rounded to exactly 30 milliliters.^[3]

The fluid ounce is a US customary unit of volume. Fluid ounces can be abbreviated as fl oz, and are also sometimes abbreviated as oz fl. For example, 1 fluid ounce can be written as 1 fl oz or 1 oz fl.

Learn more about fluid ounces.

What Is a Milligram?

The milligram is a unit of mass equal to 1/1,000 of a gram, or 0.0154 grains.

The milligram, or milligramme, is an SI unit of mass in the metric system. In the metric system, "milli" is the prefix for thousandths, or 10^-3. Milligrams can be abbreviated as mg; for example, 1 milligram can be written as 1 mg.

A milligram is also frequently referred to as a unit of weight. While technically, a milligram is a measure of mass, and weight is actually a measure of force, the two are equivalent as long as we are performing our calculations on Earth.

For example, an object with a mass of 1 milligram weighs 1 milligram on Earth, but only weighs one-sixth of that on the moon, yet still has the same mass.

Learn more about milligrams.

Fluid Ounces to Milligrams Conversion Calculator

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