Difference Between Molar mass and Molecular mass

In chemistry the substance is usually measured using molecular mass and molar mass. They are very important concepts in chemistry. Expression of molar mass is grams per mole. It can also be expressed as kilogram per mole. Molecular mass is expressed in atomic mass units.

Molecular mass:

Molecular mass of a compound is defined as the mass of one molecule. Molecular mass differs because of the isotopes. The unit in which molecular mass is measured is amu. Amu stands for atomic mass units.

Molar mass:

It is defined as the mass of substance for a given amount. The amount of molecules or atoms or compounds present in one mole of substance is given by this. Molar mass SI unit is g/mol

To make you understand how molar mass and Molecular mass is different from each other, here are the some of the major differences molar mass and molecular mass:

Difference between Molar mass and Molecular mass



Refers to mass of a mole of a substance

Refers to the mass of molecules

Also known as molecular weight

It determines the mass of single molecule

SI unit is g/mol to use in higher calculations

Measured in amu

It is defined as the mass of Avogadro number of atoms/molecules or compounds

No particular melting point

Measurement given to compounds, atoms or molecules

Determined only in molecules

Less accurate than molecular mass

Accurate to use in higher calculations

Example: Mass of 1 mole of oxygen is 15.9994 grams. Therefore the molar mass = 15.9994 g/mol


Molecular mass of Ca(OH)2 = 74 atomic mass units

These were some of the important difference between molecular mass and molar mass. To know differences between other topics in chemistry you can register to BYJU’S or download our app for simple and interesting content. India’s largest k-12 learning app with top notch teachers from across the nation with excellent teaching skills. Find notes, question papers for other subjects like Mathematics, Physics, Biology and various competitive exams as well. Enjoy learning with great experience. Learning is no more boring with BYJU’S.

Related Links:


  1. What is the relationship between molar mass and formula mass?

    1. The formula mass of a compound is the sum of the atomic masses of the atoms in its empirical formula. On the other hand, the molar mass of a compound is the mass of one mole of that compound.

Leave a Comment

Your email address will not be published. Required fields are marked *