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Molar Mass Calculator

Molar Mass Calculator

Select compound, element, and enter the molecular formula. The calculator will take moments to calculate molecular weight, nominal, hill notation, and monoisotopic mass.

Common Organic Compounds:

Periodic Table Elements:

Enter Molecular Formula

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An online molar mass calculator allows you to calculate the molecular weight, hill notation, nominal, and monoisotopic mass for given chemical formulas. In addition, the atomic mass calculator displays a pie chart for mass percentage composition by element. In this context, you can understand how to find molar mass and much more. Let’s start with some basics.

What Is Molar Mass?

In chemistry, the molar mass of a compound is defined as the mass of the compound in the sample divided by the amount of substance in the sample. Molar mass is measured in grams per mole (g/mol). Generally, the molar mass is the ratio of the mass of a substance to the number of particles it contains. It can be calculated by adding the standard atomic mass of its constituent atoms.

Molar Mass Formula:

A mole is a counting unit used to determine the number of molecules, atoms, ions, or molecular formula units in a certain compound. It is similar to other counting units, such as a pair (2) and a dozen (12). One mole of compound contains the Avogadro number of the molecule or formula unit (6.02214076 × 10^23 moles).

The molecular weight of the compound determines the mass of 1 mole of the specific substance and the number of grams per mole of the compound. In other words, the molar mass is the total mass (in grams) of all the atoms that make up one mole of a given molecule. Therefore, the unit of molecular weight is g/mol.

However, an online Chemical Equation Balancer Calculator finds a balanced equation and equilibrium constant with chemical names and formulas.

Table of Molar Masses:

When you want to determine the molecular weight of  different molecules, then put these weights in the molar mass equation to find the total weight of a molecule:

Molar Mass

Total Molecular Weight

molar mass of H20


molar mass of O


molar mass of C


molar mass of N


Ca molar mass


molar mass of S


Ne molar mass


Ar molar mass


molar mass of He


Pb molar mass


molar mass NO


molar mass of I


B molar mass


molar mass Cr


molar mass F


molar mass of CS



How to Calculate Molar Mass of a Compound?

Step 1. The molar mass calculator uses the chemical formula to determine the number of atoms of each element in the compound.

Step 2. Now, the molecular weight calculator multiplies the atomic weight of each element by the number of atoms present in the compound.

Step 3.  Then, molecular formula calculator Puts everything together and specify the unit of measurement as grams/mole.

However, an online Ideal Gas Law Calculator determines the unknown measurable properties of the ideal gas law equation.

Example 1.

What is the molar mass of sodium carbonate Na2CO3?


Since sodium carbonate contains one carbon atom, two sodium atoms, and three oxygen atoms, the molecular weight is

Na : 23.0 x 2  =  46

C : 12.0 x 1 = 12

O : 16 x 3= 48

If molecular formula calculator add up the total value, which is 12 + 46 + 48 = 106

Therefore, the molar mass of Na2CO3 is 106 g/mol.

Example 2:

In the NaOH compound, the molar mass of Na alone is 23 g/mol, the molar mass of O is 16 g/mol, and the molar mass of H is 1 g/mol. What is the molar mass of NaOH?


Na + O + H = NaOHa + O + H = NaOH

Now, molecular mass calculator add all masses of substances together:

16 g / mol + 23 g / mol + 1 g / mol = 16 g / mol + 40 g / mol 23 g / mol + 1 g / mol = 40 g / mole

The molar mass of the NaOH compound is 40 g/mol.

Avogadro’s Number:

Amedeo Avogadro is considered to be the number of units (usually molecules or atoms) in a substance that is proportional to its physical mass. Amadeo Avogadro first proposed that at a given temperature and pressure, the volume of a gas is proportional to the number of atoms or molecules, and has nothing to do with the type of gas.

Although he did not define the exact ratio, he owes the idea to him. The Avogadro number is the proportion that relates the molar mass on the atomic scale to the physical mass on the human scale. Avogadro’s number is defined as the number of elementary particles (atoms, molecules, compounds, etc.) per mole of matter, equal to 6.022 × 10^23 mol^{-1}, represented by the symbol NA.

The Mole:

Mole (abbreviated as mol) is an SI measurement of the number of “chemical objects” such as atoms, protons, or electrons. It is defined as the amount of matter that contains as many particles as there are atoms in 12 grams of pure carbon-12. So, 1 mole contains 6.022 × 10^{23} basic units of molar mass.

Chemical Computations with Mole and Avogadro’s Number:

Avogadro number is necessary for understanding the composition of molecules and their interactions and combinations. For example, since two hydrogen atoms will combine with one oxygen atom to form a water molecule (H2O), two moles of hydrogen (2 × 6.022 × 1023 hydrogen atoms) will combine with one mole of oxygen (6.022 × 1023 oxygen atoms) to form One mole of H2O.

Another property of Avogadro’s number is that the mass of one mole of a substance is equal to the molecular mass of that substance. For example, the water molecular weight is 18,015 atomic mass units (AMU), so a mole of water weighs 18,015 grams. This feature simplifies many stoichiometric calculations.

If you have 1.25 grams of molecules with a molecular weight of 134.1 g/mol, how many moles do you have? 25 grams x 1 mol / 134.1 grams = 0.0093 mol

How Molar Mass Calculator Works?

Use an online molecular weight calculator to work out the molar mass of chemical compounds by following steps:


  • You can find the molar mass by either common organic compounds, the periodic table, or by entering a complete molecular formula.
  • Hit the “Calculate Molar Mass” button.


  • The molar mass calculator displays a table with the number of atoms, molar mass, and subtotal mass.
  • The atomic mass calculator also provides the hill notation, empirical formula, the nominal and monoisotopic mass of the given substance.


What is the use of the mole concept?

The mole is the unit of measurement for the mass of a chemical substance. This connects the atom to the amount of macroscopic material with which we work in the lab. This allows the chemist to weigh two substances, such as sulfur and iron, to obtain the same number of sulfur and iron atoms.

What is the empirical formula?

In chemistry, the empirical formula of a compound is the simplest positive integer ratio of the present atoms in the compound.

Why we use Monoisotopic mass (Mmi)?

Mmi is one of the different types of molecular weights used in mass spectrometry. The theoretical monoisotopic mass of the molecule is calculated by summing the precise masses (including mass defects) of the most abundant natural stable isotopes of each atom of the molecule.

How many grams does a mole contain?

The number of grams in moles depends on the substance you have. To calculate it, find the molecular mass or atomic mass of your substance and multiply it by the number of moles you have. For one mole, the molecular mass or atomic mass will be the same as the weight.


Use this online molar mass calculator to find the molar and percent mass composition of the linear chemical formula. Also, this online molecular mass calculator will recognize the entered formulas that are included in the drop-down list of organic compounds.


From the source of Wikipedia: Molecular Weight, Molar masses of elements, Molar masses of compounds, Average molar mass of mixtures.

From the source of Lumen Learning: Avogadro’s Number and the Mole, Chemical Computations with Avogadro’s Number and the Mole, Converting between Moles and Atoms, Moles and Atoms, Measuring Mass in Chemistry.

From the source of Libre Text: Isotopic atomic mass, Percentage of Composition, use of the mole concept.