Difference Between mg and mcg (With Table)

Measurement is quantifying an object with its attributes to compare it with other objects or events. It is the process of associating numbers with the physical quantities of an object like mass, length, time, etc. The metric system is the standard system of measurement and is also known as the International System of Units (SI Unit System).

In the metric system, “mg” and “mcg” are both terms of measurement of mass. They are very small units of measurement. Where “mg” stands for “milligrams”, “mcg” stands for “micrograms”. 

Various food packets show their nutrient content in mgs and mcgs. They are also used to indicate the content of certain ingredients in cosmetics, drugs and other medicines. 

mg vs mcg

The main difference between mg and mcg lies in it’s size. Milligram is equal to 10-3 gram and a microgram is equal to 10-6 gram. Both of them are widely used in drug chemistry and nutritional value calculations.

A microgram is equal to 0.001 milligrams, hence it is much smaller than a milligram. The main difference between mg and mcg lies in their sizes. While a milligram is 1000th of a gram, a microgram is 100000th of a gram.

Conversion between milligram and microgram is very easy and one can do so by dividing or multiplying the given number by 1000.

2 mg = 2×1000 mcg

           = 2000 mcg

2 mcg = 2÷1000 mg

             = 0.002 mg

Comparison Table Between mg and mcg

Parameters of Comparison




mg is the abbreviated form of a milligram.

mcg is the abbreviated form of a microgram.


‘Milligram’ has the prefix ‘milli’.

‘Microgram’ has the prefix ‘micro‘.


Bigger in size. An mg is 1000th of a gram.

Smaller in size. An mcg is 1000000th of a gram.


Only written as mg.

Also written as μg.

Frequency of use

Used more frequently in daily life due to it’s a bigger size.

Used less frequently every day due to a smaller size.

What is mg?

A milligram is the 1000th part of a gram. It comes under the metric system of measurement of weight of a substance. It is used in our daily lives by the common man. We can easily measure a substance to the required amount by a weighing scale.

This measurement is also used to indicate the distribution of nutrients in food labels. It tells us how much mgs of vitamins and minerals are present inside a particular food product. The unit of ‘mg’ is also used in making drugs, it measures the dosage of a particular ingredient.

The tool used to measure milligrams is known as a milligram balance. It gives us the exact measurement to the unit of milligrams, and not any further. It is usually found in a scientific or a pharmaceutical laboratory. They make use of the balance in carrying out experiments and measuring the dose of a particular drug.

To convert milligrams into grams, the value should be divided by 1000.

1000 mg = 1000 ÷ 1000

 = 1 gm

And to convert grams milligrams into micrograms, the value should be multiplied by 1000.

1000 mg = 1000 × 1000

               = 1000000 mcg

What is mcg?

A microgram is 1000000th part of a gram. It is also used to measure the mass of a substance. It is much smaller than the gram and not used by us in our daily lives. 

A microgram is mostly used in carrying out scientific experiments and in producing drugs. Most medicines we use contain certain micrograms of the dose of a drug. It is used less frequently due to its minimal requirement in measuring materials in daily life.

Micrograms are measured by a microgram balance. This gives us the precise measurements to the unit of micrograms. This device is more precise than a milligram scale. It is also used in laboratories.

To convert micrograms into grams, the value should be divided by 1000000.

1000 mcg = 1000 ÷ 1000000

                 = 0.001 gm

And to convert micrograms into milligrams, the value should be divided by 1000.

1000 mcg = 1000 ÷ 1000

                 = 1 mg

Main Differences Between mg and mcg

  1. Milligram is also known as ‘mg’ while microgram is also known as ‘mcg’.
  2. Both microgram and milligram have different prefixes, them being ‘micro’ and ‘milli’ respectively.
  3. mcg is smaller than mg.
  4. A microgram can be symbolised as μg, whereas there’s no other symbol for milligram than mg.
  5. Milligram is used more in daily life while microgram is used less often.


Measurement is important and is seen in almost all aspects of our lives. From weighing a few kilos of vegetables to figuring out the mass of a planet, measurement is used in all. The measurement of mass of an object is usually done in kilos, as it is the standard unit. Milligram and microgram are both smaller parts of a kilogram.

Both milligram and microgram are a part of the metric system for the measurement of mass. The difference lies in their minuteness. They are both smaller than a gram; milligram by a 1000th and microgram by a 1000000th.

Milligrams and micrograms both measure less than the standard unit of measurement of mass that is kg or a “kilogram”. If a substance is measured up to milligrams and micrograms, it gives us precise measurements. Micrograms are more precise than milligrams.

The food industry sees a lot of usage of mgs. The nutrient content breakdown as seen on food labels is measured in milligrams. It tells us about how many mgs of protein/fat/carbohydrates are present in a particular food product.

Producing drugs and conducting experiments in a lab requires taking a very little amount of substance to reach the objective. Such procedures make use of micrograms of the ingredients required to make the drug or to carry out the experiment. The dosage of drugs is usually given in mcgs. 

Milligrams and micrograms are both measured by the milligram balance and the microgram balance respectively. They give precise and accurate measurements of the unit of mass.