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falkowskiphd eNotes educator| Certified Educator

Mass is "the amount of stuff" in an object. That is, the amount of atoms and molecules present.  Mass in science, is measured in the metric system using units such as kilogram (about 2.2 pounds)nwhich are a thousand grams, grams, centigrams (hundredths of grams), and milligrams  (thousandths of grams).  Mass is different from weight,  Weight is a force.  It depends on gravity pulling us toward the center of our planet (or another planet if we ever get there or the moon).  If we weighed ourselves on our bathroom scale and noted our weight and then took our scale with us to the moon, we would find that our weight was only one sixth as much there because the force of gravity is much smaller.  However, because when we find mass, we use a procedure that compares our object with known mass, our mass would not change regardless of the amount of pull of gravity.  This explains why astronauts did not change their size when they were on the moon even though their weight decreased considerably.  Well, OK, that's not exactly true.  Their size changed just a little. They were temporarily a tiny bit taller because gravity was not pulling them down, compressing their spines a little bit.  But that has nothing to do with the definition of mass.

enotechris eNotes educator| Certified Educator

Mass is a property of matter, and its units are usually measured in grams (g) or kilograms (kg) worldwide and additionally ounces (oz) and pounds (lbs) in the US.  On the small scale, atomic mass, or the mass of elemental particles (protons, neutrons, electrons, and whole atoms) are measured relative to an atom of carbon-12, which is set to have a mass of 12.0000. Mass should not be confused with weight, which a measurement of how heavy matter is when subject to the force of gravity, so:

weight = (mass) * (force of gravity)  or w=mg.

leotor | Student

unit of mass and convertions are as follows:

in metric:

milligram = 0.001 gram
1 centigram = 0.01 gram
1 decigram = 0.1 gram
1 kilogram = 1000 grams

in english:

1 slug = 14.5939 kilogram

1 kilogram = 0.068521779 slugs

Pounds and ounces are not the unit of mass but a unit of Weight. Weight is different from a mass because a mass becomes weights if it is subjected to a gravitational force or acceleration. The weight of objects at sea level is different when the object is placed at a higher elevation or when the object is placed in moon where there is no gravity there.

adarshanurag | Student

A unit of mass is a unit in which the amount of matter contained in a substance is measured.

The SI unit of mass is Kilogram(kg).

Other common units are tonne, pound, quintal, etc... 

alejandrogalarce | Student

The property a body has of resisting any change in its state of rest or uniform motion is called inertia. The inertia os a body is related to what we think of as the amount of matter it contains. A quantitative measure of inertia is mass: The more mass a body has, the less its acceleration when a given net force acts on it. The SI unit of mass is the kilogram (kg).

source: Applied Physics, 2012.

astrosonuthird | Student

Mass = Mass is the amount of material in an object.


Weight = Weight is the gravitational force acting on a body mass.



The SI unit of mass is ( kg )


See you next time


brooklynlotus | Student

A unit of mass is a measurement of mass. It is actually a measurement of how much matter there is.The closest concept is weight. Let's understand the difference between weight and mass. A 50 lb. dumbell is twice the mass of a 25lb. weight.If these dumbells are on the surface of the moon,they will weigh less because of less gravitational pull.The change of weight might be seen by being able to lift the weights with two fingers as though it was styrofoam.So weight is variable in relation to gravitational pull.However the ''amount of matter'' or ''mass'' did not change when it was on the moon.

One way of measuring mass is used in particle physics. The ''atomic weight''( despite it's name) is one scale used to measure the mass of different elements.Hydrogen has an atomic weight of 1. It contains one proton.Helium has an atomic weight of 4 and its nucleus has 2 protons + 2 neutrons.

matthew0109 | Student

Mass is the amount of matter in an object and the unit of mass is kilogram (kg).

An example of a unit of mass would be gram, but it can also be kilogram. There can be many examples this is just one of them.

zumba96 | Student

The SI unit of mass is the Kilogram. Mass is used in weights or scales. Pounds are ounces are units of weights, not units of mass. 

maria-vivanco | Student


cathyluv | Student

Many may find it difficult or confusing to differentiate mass from weight. Mass is how much matter an object contains while weight is the force of gravity acting upon that object. Therefore, the SI unit of weight is N (Newton) while that of mass is kg (kilogram).

Wiggin42 | Student

Mass is the measure matter. Its often confused with weight which is just a gravitational force. The SI unit for mass is Kilogram. The SI unit for force is Newton. 

One way to think of it as that a person's mass will stay the same regardless of the gravity of a planet. A person on Earth will have the same mass as a person on the Moon. 

But the weight, the gravitational force, will be different. 

A Unit of mass can be a gram or kilogram. 

zumba96 | Student

The SI unit of mass is the kilogram (kg). As mass is difficult to measure directly, usually balances or scales are used to measure the weight of an object, and the weight is used to calculate the object's mass.

maria-vivanco | Student

The actual SI unit is kilogram. 

However the conversion units are as followers (like if the problem wants you convert to grams, milligrams etc)

milli gram = 0.001 gram
1 centi gram = 0.01 gram
1 deci gram = 0.1 gram

1 deca gram= 10 grams

1 kilo gram = 1000 grams

parama9000 | Student

There are two types of units SI and Imperial.

laurto | Student

The SI unit for mass is the kilogram (kg).

I see many answers that include grams and milligrams but these are just units of measure, while the kilogram (kg) is the actual SI unit.

twainlover13 | Student

gram, kilogram, decigram, etc

sargam21 | Student

Mass is the Property of matter and is usually measured in grams and


saransh2012 | Student

the SIunit of mass is kilogram(kg)

aabbeir | Student

Mass is the amount of matter in an object. The SI base unit is kilograms (kg). Mass is NOT weight. Weight is correctly measured in Neutons and it is a measure of gravitational force.

jphanuels | Student

The SI unit of mass is kilograms but there other derived units like tonnes, metric tonnes e.t.c

qed | Student

The metric unit of mass is 1 kilogram, as represented by the International Prototype Kilogram stored in Paris.

The gravitational pull that the Earth exercises towards a 1-kilogram mass is 1kg * 1 G = (roughly) 9.81 kgm/s2 = 9.81 Newton. Note that the Earth's gravitational pull varies by 1% depending on where you are on the Earth.

An earlier answer suggested that the Moon has no gravity. Not true. The gravitational pull of the Moon is roughly 1/6 of Earth's gravity. The Standard kilogram would therefore weigh some 0.166 kilograms in the Moon.

idiot101 | Student

grams, milograms, micrograms, all in the metric system.

uranium9 | Student

There are many units of mass.In S.I ,unit of mass is kilogram(kg),in C.G.S ,gram(g),in F.P.S,pound(lbs).

friendjoy | Student

unit of mass is kg(kilogram) in si system and g(gram) in cgs system..

hazie123 | Student

The unit of mass is the kilogram (kg), but commonly, when we measure something in kilograms, we are measuring the force of gravity on that mass, which should be measured in newtons (N), (a measure of force). However, if we used a balance, measuring an object against a standard mass, then our result would be independent off the strength of gravity in that place and so it would not matter if we were on Earth or on the moon our, measurement would be the same (i.e: a measurement of the mass which never changes, wherever you may be).

sid-sarfraz | Student


What is a unit of mass?


Mass is the total amount of matter in an object. Basically it is the total weight of an object in terms of kilogram for large objects, grams for small objects and for very small objects milligrams is used.

1 kilogram = 1000 grams

Further it can be divided into gram, centigram, milligram etc.

mohem | Student

The SI unit is the kilogram

nicole8923 | Student

The SI unit for mass is kg

Jyotsana | Student

A unit of mass are gram, kilogram, decigram etc..

mrstyndall | Student

gram, killogram, milligram

alineisstuding | Student

The definition of unit of mass is very simple, here it is: A unified body of matter with no specific shape: a mass of clay

bergcar | Student


akshay123456789 | Student

Mass is the amount of matter contained in a substance.

The unit of mass is Kilogram(Kg).

hyunjae | Student

the unit for mass is kilograms and the unit for weight is kg m/s^2 or Newton (N).

shados97 | Student

Kg kilograms

joy1495 | Student

The amount of constituent particles that a matter contains is said to be its mass. Its very different in respect to weight. It is common misconception that mass and weight are almost same but they are very different infact. Coming to the point the SI units of mass is kilogram(Kg).

azzyj | Student

kilogram (kg)

sid464666 | Student


javaria95 | Student

The Gram is the standard metric (and SI) unit of mass.

I believe that the kilogram is now the standard metric and SI unit and the gram is defined as 1/1000 of a kilogram 


shivadatta | Student

The SI unit of mass is Kilograms (Kg).

1 Kg = 1000gm

and gm molecular mass of any substance is equal to 1 mole.

saransh2012 | Student



enotessophia10 | Student


swetank | Student


The ammount of matter contained in a body is can be termed as mass.

According to different system of unit are used in the different parts of the world. These systems are mainly the methods of defining the three fundamental units. The most widely used system of units is CGS or French or metric system.

In 1960, at Eleventh General Conference on Weights and Measures held at Paris, an international system of units is adopted to have a consitent system of units and also to simplify the communications amon the scientists. This system of units is known as Le Systeme International d' Unites abbreviated as SI units.

  • C.G.S. or French or Metric System: This system was originated in France but now it is used in the scientific measurements and also is widely used throughout the world. In this system, the unit of length is centimetre, the unit of mass in gram and the units of time is second. From the initial letters of the words centimetre, gram and second this system is called the C.G.S. system.
  • S.I. units: In this system in addition to units of length, mass and time, units of electric current, temperature, luminous intensity and quantity of substance i.e., seven basic units in all are adopted. These are-


PHYSICAL QUANTITY                     UNIT                           SYMBOL

1. length                                      metre                           m

2. mass                                       kilogram                       kg

3. time                                        second                         s

4. electric current                         ampere                         A

5. temperature                             kelvin                           K

6. luminious intensity                    candela                         cd

7. quantity of a substance             mole                            mol

nado | Student

the unit of mass is KG(s)

Yojana_Thapa | Student

SI unit of Mass

  • g, km, lbs
avanish | Student
  • Please do not ask such stupid questions
cooldarena | Student


lena101 | Student