Difference Between Milligram and Microgram

Milligram and Microgram are the metrics that are used to measure the weight of something. One milligram equals to one part of a thousand grams. One microgram is lighter than one milligram and equals to one part of a million grams. These are internationally accepted metric systems and are used worldwide.

Milligram vs Microgram

The main difference between Milligram and Microgram is that one milligram is one part of a thousand grams whereas a microgram weighs one part of a million grams. Milligram is an SI metric used to weigh light objects while microgram is the SI unit of weighing even lighter particles.

Milligram vs Microgram

One milligram is one by thousand part of a gram. It can also be calculated in terms of grams as a thousand milligrams equals to one gram. The abbreviation of milligram is mg. It is originated from the French word milligramme. Mathematically, it is equal to 0.001 grams. It can be used to calculate the mass and weight of light particles.

A microgram is even lighter than a milligram. It is one-millionth part of a gram. One million milligrams equals one gram. It is also a part of one thousand milligrams. Microgram is abbreviated as mcg. The abbreviation of microgram is originating from Greek. Mathematically, it is equal to 0.000001 grams. It is used to weigh very light particles.


Comparison Table Between Milligram and Microgram (in Tabular Form)

Parameter of ComparisonMilligramMicrogram
AbbreviationMilligram is abbreviated as mg.Microgram is abbreviated as mcg.
Parts in gramA thousand milligrams is equal to one gram.One million micrograms is equal to one gram.
Metrics1mg = 1/1000 g1mcg = 1/1000000 g
ConversionMg = mcg*1000Mcg= mg/1000
ToolThe tool used to calculate a quantity in milligram is milligram balancesThe tool used to calculate a quantity in microgram is microgram balances


What is Milligram?

A milligram is a unit of mass that is used to weigh quantities. It is comparatively a very small unit when compared to kilograms, which is the SI unit of mass. When expressed according to grams, one milligram is equal to one by thousand part of a gram. This implies that a microgram is very tiny in terms of quantity.

One milligram is equal to 1* 10-3 grams. One gram is equal to the mass of a millimeter. It also equals one-thousandth of a liter provided that the water is at a temperature of 4 degrees Celsius.  It is also said that one gram is the equivalent to 0.0154 grain. One milligram is equal to one-millionth of a kilogram.

Often, milligrams are used worldwide to express the limitation of a quantity. This is why it is always expressed in grams. This explains and clears us that the amount is very small. These conversions are taught to us at lower grades, so that the idea of the quantity is thorough. All over the world, many quantities are expressed in milligrams.

The nutrition details in the daily foods we consume are expressed in terms of milligrams. When the wrappers of the packets that contain fast foods are checked, the packagers express the quantity of fats, vitamins, and minerals in terms of milligrams.


What is Microgram?

One microgram is also a unit of mass that is used to weigh particles. This is even smaller than milligrams. Since kilogram is a very huge amount compared to microgram, micrograms are often expressed in terms of grams. One microgram is equal to one-millionth of a gram. This makes it clear that milligram is not a quantity that can be identified by the naked eye.

One microgram is equal to 1*1000000 grams. This unit is mostly used in microchemistry. The symbol of microgram is mcg. The ancient symbol mu is derived from Greek.  This Greek symbol is accepted by the International System of units. But in the United States of America and the United Kingdom, the unit used is mcg.

Microgram is been taught at schools to understand the details of the number of compounds that is present in different substances. This amount as is very tiny is often represented by converting it to grams. At higher levels, the students who graduate in microchemistry and microbiology use this unit to measure the compounds obtained by analyzing them in labs.

Institutions such as the Institute for Safe Medication Practices and the US Food and Drug Administration encourage the practice of expressing quantities in micrograms. This is because of the importance of composition in drugs. Even if a microgram is added or deducted from the composition, the drug may get overdosed, and hence it is a danger to the human community.

Main Differences Between Milligram and Microgram

  1. One milligram is equal to one by a thousand parts of a gram. One microgram is equal to one by million parts of a gram.
  2. When expressed in terms of grams, thousand milligrams is equal to a gram whereas one million micrograms together contribute a gram.
  3. Milligram is lighter than gram but heavier than microgram. Microgram is lighter than both gram and milligram.
  4. Milligrams can be converted to micrograms by multiplying it by thousand. Micrograms are converted to milligrams by dividing it by thousand.
  5. The equipment used to weigh quantities in milligrams is known as milligram balance whereas the equipment used to weigh particles in microgram is known as microgram balance.



Both milligrams and micrograms are units that are used to measure mass. One milligram is approximately one-thousandth part of a gram. From this, it is clear that the amount that a milligram expresses is very small. This unit is used to express nutrition in the food industry. When the unit amount of food is consumed, the amount of nutrition that one intake is expressed in mg.

Microgram is even lighter than milligram. A microgram is approximately one-millionth part of a gram. This is a tiny quantity and hence it is always expressed in terms of grams rather than expressing it in terms of kilograms which is the standard unit used otherwise. The medical industry uses this unit to express the quantity of vitamins and minerals that should be present in the medicine.


  1. https://www.medicinenet.com/script/main/art.asp?articlekey=12079
  2. https://www.dictionary.com/browse/microgram
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