Unit of Mass

What is the Unit of Mass?

Students should learn about mass, as it is very important before understanding the unit of mass. In simple words, mass is the quantity of matter in an object. It can be considered as both a property of a physical body as well as measurement of its resistance to acceleration when some quantity of force is applied. However, the important point a student should remember is that mass is different from weight even though the term might sometimes be used interchangeably, as they have different units.

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The matter which is present in a given object is known as mass, and the most commonly used units of measurement are:

  • Gram

  • Kilogram

Mass can also be termed as the amount of atoms and molecules present.  In science, mass is measured in metric system units using kilogram (a thousand grams), grams, centigrams (hundredth of grams), and milligrams (thousandth of grams).

Unit of mass

a. SI Unit of Mass

The standard unit of mass is Kilogram (kg)

In SI units, following units are accepted: gram (g) and its multiples and submultiples, a tonne (t) or metric ton, electronvolt (eV), the atomic mass unit (u) which is most convenient for denoting the masses of atoms and molecules.

b. Cgs Unit of Mass

Centimeter gram second, otherwise the CGS system of unit is metric type system based on centimeter as unit of length, gram as unit of mass, and second as unit of time.

Some Common Units of Mass:

Milligram (mg)

0.001 gram or 1/1000 gram

Decigram (dg)

0.1 gram or 1/10 gram

Centigram (cg)

0.01 gram or 1/100 gram

Gram (g)

1,000 milligrams

Decagram (dag)

10 grams

Hectogram (hg)

100 grams

Metric ton (t)

1,000 kilograms

Kilogram (kg)

1,000 grams


Metric Units of Mass

To measure the weight of an object, mass is used. For example, when you step on a scale, you measure the mass of your body.

The most common units to measure mass in the metric system are gram and kilogram.

How Much is a Gram?

Mass of a small paperclip is about 111 grams.

How Much is a Kilogram?

Mass of a wooden baseball bat is about 111 kilogram.

Measurement of Mass

The amount of matter within an object is represented by mass, but measuring mass doesn't necessarily mean that you have measured weight since weight changes due to gravity's effect. However, mass does not change regardless of where the object is located, the amount of matter remains the same. Depending on the size and location of objects, scientists use various tools to measure mass.

Mass is measured by a beam balance device, also known as mass scales, balance scale, simply scales, mass balance, weight scales, or weight balance.

As mentioned above, a number of tools exist for measuring mass in different environments like balances and scales, measurement transducers, Newtonian mass measurement devices, vibrating tube sensors, and use of gravitational interaction between objects.

a. Balances and Scales

For daily use objects, scientists use a balance to obtain the object's mass. One of the examples of balance is triple beam balance. There are different types of balance, which include beam balances and digital scientific balances. In space, scientists use inertial balance to measure mass.

b. Measurement Transducer

Sometimes mass cannot be determined by using a balance. Transducers are used by the scientists to measure the mass of a liquid in a calibrated tank. It also measures the mass when properties of the liquid are in a static state. A signal is sent to the processor through a transducer, which makes the mass calculations displayed by an indicator. Taking measured mass of liquid below the transducer, and subtracting mass of vapor, mass of a floating roof, mass of bottom sediment and water yields gross mass.

c. Space Linear Acceleration Mass Measurement Device (SLAMMD)

SLAMMD is one of the most sophisticated mass measuring devices used to measure the mass of humans in orbit, currently stationed on the International space station. SLAMMD is a piece of rack-mounted equipment that is based on Sir Isaac Newton's law of motion, where force equals the product of mass and acceleration. By using two springs that exert force against a person, this device determines the person’s mass via force and acceleration.

FAQ (Frequently Asked Questions)

1. What is the Difference Between Mass and Weight?

Ans- The quantity of matter within an object is known as mass. This is a constant quantity measured in kilograms and is scalar.

Whereas the force with which an object gets pulled toward earth is known as weight, which is not a constant quantity and is measured in Newtons and is a vector quantity.

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Other difference with example:

If we weigh ourselves on a room scale and note the weight and then take our scale along with us to the moon, we would discover that our weight was only one-sixth as much there since the force of gravity is smaller.

But in case of mass, we use the procedure of comparing the object with known mass. Also, mass doesn't change regardless of the amount of pull of gravity.

Weight should not be confused with mass, which is a measurement of how heavy matter is when subject to the force of gravity.

So, weight=(mass)*(force of gravity), or

W= mg.

2. Give Some Examples for Conversion of Mass.

Ans- Converting kilograms to grams

1 kilogram=1000 grams

To convert kilograms to gram, we multiply by 1000 to the number of kilograms.


7 kilograms= 7×1000= 7000 grams

Converting grams to kilograms

1 gram=1000​ kilograms

By dividing 1 kilogram with 1000, we get the conversion in grams


8g = 8÷ 1000 = 0.008 kg

3. What is the Largest Practical Unit of Mass?

Ans- Chandrasekhar limit (CSL) is the largest practical unit of mass.

Mass is independent of physical conditions like pressure, temperature, or location.

Like length, the mass of many entities in this universe can vary from as light as 10–31 kg (electron) to as massive as the universe of the order of 1055 kg. Some of the units, such as Quintal=100 kg,1 metric ton=1000 kg, Slug=14.57 kg, are commonly used.

1CSL=1.4 times the mass of sun.

Nuclear or atomic masses are made in terms of a unit called amu (atomic mass unit).

4. If Kg is Unit of Mass, then What's the SI Unit of Weight?

Ans- SI unit of weight is Newton

According to following equation


We know that weight of object is force on it of gravity

So, F=Weight

As mentioned above, 

SI unit of Weight=Force=Newton(N)