Gallons to Milligrams Conversion Calculator

Enter the volume in gallons below to calculate the weight in milligrams.


Result in Milligrams:

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1 gal = 3,785,411.7840007 mg
1 gal = 3,785.411784 g
1 gal = 3.785412 kg

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How to Convert Gallons to Milligrams

Since gallons 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 gallons 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.

Gallons to Milligrams Formula

To convert a measurement in gallons 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 gallon (mg/gal).

If the density is given in grams per milliliter (g/mL), then first multiply the density by 3,785,411.78 to convert to mg/gal.

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

milligrams = gallons × 3,785,411.78 × density

Thus, the weight in milligrams is equal to the volume in gallons multiplied by 3,785,411.78 times the density (in g/mL) of the ingredient, substance, or material.

For example, here's how to convert 5 gallons to milligrams for an ingredient with a density of 0.7 g/mL.
milligrams = 5 gal × 3,785,411.78 × 0.7 g/mL = 13,248,941.24 mg

When to Convert Gallons to Milligrams

Gallons 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]

A third application of weight and volume conversions is when shipping freight when calculating the volumetric weight for cargo and packages. Trucks, ships, and airplanes are limited in the amount of weight or volume they can transport, so if one of those quantities is known, but the limitation is on the other, then it becomes necessary to convert between the two so as not to overload the shipping vehicle.

Keep reading to learn more about each unit of measure.

How Many Milligrams Are in a Gallon?

The actual weight of a gallon 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 gallon.

Gallon measurements converted to milligrams for commonly used cooking and baking ingredients.
Volume in Gallons: Weight in Milligrams of:
Water Milk Cooking Oil All Purpose Flour Granulated Sugar
1/8 gal 473,176 mg 487,372 mg 416,395 mg 250,310 mg 400,000 mg
1/4 gal 946,353 mg 974,744 mg 832,791 mg 500,621 mg 800,000 mg
1/3 gal 1,261,804 mg 1,299,658 mg 1,110,387 mg 667,494 mg 1,066,667 mg
1/2 gal 1,892,706 mg 1,949,487 mg 1,665,581 mg 1,001,241 mg 1,600,000 mg
2/3 gal 2,523,608 mg 2,599,316 mg 2,220,775 mg 1,334,989 mg 2,133,333 mg
3/4 gal 2,839,059 mg 2,924,231 mg 2,498,372 mg 1,501,862 mg 2,400,000 mg
1 gal 3,785,412 mg 3,898,974 mg 3,331,162 mg 2,002,483 mg 3,200,000 mg

What Is a Gallon?

The US liquid gallon is a unit of fluid volume equal to four quarts, eight pints, or sixteen cups.[3] The US liquid gallon should not be confused with the US dry gallon or the imperial gallon, which are different units of measure.

The gallon is a US customary unit of volume. Gallons can be abbreviated as gal; for example, 1 gallon can be written as 1 gal.

Learn more about gallons.

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.


  1. National Institute of Standards & Technology, Culinary Measurement Tips,
  2. CK-12 Foundation, Introductory Chemistry (CK-12) - 12.6: Mass-Volume Stoichiometry,
  3. National Institute of Standards and Technology, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, Handbook 44 - 2019 Edition,

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