Molar Mass & Molecular Weight Calculator

Calculate the Molar Mass of Compounds and Elements

Enter a chemical formula (e.g., H2O, NaCl, C6H12O6) to calculate its molar mass and molecular weight. Get a detailed breakdown of each element's contribution, and convert between mass and moles.

Example Calculations

Try these sample formulas to see how the calculator works.

Water (H2O)

Simple Compound

Calculate the molar mass of water and convert 18 grams to moles.

Chemical Formula: H2O

Mass (g): 18 g

Moles (mol): mol

Sodium Chloride (NaCl)

Ionic Compound

Find the molar mass of table salt and convert 0.5 moles to grams.

Chemical Formula: NaCl

Mass (g): g

Moles (mol): 0.5 mol

Glucose (C6H12O6)

Organic Compound

Calculate the molar mass of glucose and convert 180 grams to moles.

Chemical Formula: C6H12O6

Mass (g): 180 g

Moles (mol): mol

Iron (Fe)

Element

Find the molar mass of iron and convert 55.845 grams to moles.

Chemical Formula: Fe

Mass (g): 55.845 g

Moles (mol): mol

Other Titles
Understanding the Molar Mass & Molecular Weight Calculator: A Comprehensive Guide
Master molar mass calculations, conversions, and chemical formula analysis with this all-in-one chemistry tool.

What is Molar Mass?

  • Definition and Importance
  • Molar Mass vs. Molecular Weight
  • Units and Measurement
Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol). It is a fundamental property in chemistry, used to relate the mass of a substance to the number of particles (atoms, molecules, or ions).
Molar Mass vs. Molecular Weight
While often used interchangeably, molar mass refers to the mass per mole (g/mol), whereas molecular weight is a dimensionless number comparing the mass of a molecule to 1/12 the mass of a carbon-12 atom.

Molar Mass Examples

  • The molar mass of H2O is 18.02 g/mol.
  • The molecular weight of NaCl is 58.44.

Step-by-Step Guide to Using the Molar Mass Calculator

  • Input the Chemical Formula
  • Calculate Molar Mass and Breakdown
  • Convert Between Mass and Moles
Enter the chemical formula of your compound or element. The calculator parses the formula, identifies each element and its count, and retrieves atomic masses from the periodic table.
Detailed Elemental Breakdown
The calculator provides a table showing each element, its count, atomic mass, and subtotal contribution to the total molar mass.
Mass-Mole Conversions
You can enter a mass (in grams) to convert to moles, or enter moles to convert to mass, using the calculated molar mass.

Usage Examples

  • 18 g H2O = 1 mol
  • 0.5 mol NaCl = 29.22 g

Real-World Applications of Molar Mass Calculations

  • Chemistry Education and Exams
  • Laboratory and Industrial Uses
  • Pharmaceuticals and Environmental Science
Molar mass calculations are essential in chemistry education, laboratory research, and industry. They are used in stoichiometry, solution preparation, and quality control.
Pharmaceutical Applications
Pharmacists use molar mass to calculate dosages and prepare solutions accurately.
Environmental Science
Scientists use molar mass to analyze pollutants and chemical reactions in the environment.

Application Examples

  • Preparing 1M NaCl solution requires 58.44 g NaCl per liter.
  • Calculating CO2 emissions by molar mass.

Common Misconceptions and Correct Methods

  • Formula Parsing Errors
  • Element Symbols and Counts
  • Mass-Mole Conversion Mistakes
A common mistake is miswriting element symbols (e.g., 'co' instead of 'CO'). Always use correct capitalization and check the periodic table.
Counting Atoms Correctly
If no number is written after an element, it is assumed to be 1. For example, NaCl has 1 Na and 1 Cl atom.
Conversion Pitfalls
Always use the calculated molar mass for conversions. Double-check units and input values for accuracy.

Misconception Examples

  • 'H2O' is correct, 'h2o' is not.
  • 'CO' (carbon monoxide) is different from 'Co' (cobalt).

Mathematical Derivation and Examples

  • Molar Mass Formula
  • Worked Calculation Examples
  • Stoichiometry and Conversions
Molar mass = sum of (atomic mass of each element × number of atoms). For H2O: (2 × 1.008) + (1 × 15.999) = 18.015 g/mol.
Example Calculations
Convert 36 g of H2O to moles: 36 / 18.015 = 2 mol. Convert 0.25 mol NaCl to grams: 0.25 × 58.44 = 14.61 g.
Stoichiometry in Reactions
Use molar mass to relate reactants and products in chemical equations. For example, 2H2 + O2 → 2H2O: 4 g H2 + 32 g O2 produce 36 g H2O.

Derivation Examples

  • Molar mass of C6H12O6: (6×12.011)+(12×1.008)+(6×15.999)=180.156 g/mol
  • 1 mol Fe = 55.845 g