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Use this free Molecular Weight Calculator to instantly compute the molar mass (g/mol) and molecular weight of any chemical compound, molecule, or formula unit by entering its chemical formula. The calculator automatically parses the formula, looks up the standard atomic weights of each element from the IUPAC periodic table, and sums all contributions using the formula: MW = Σ (atomic mass × number of atoms) — supporting all 118 elements of the periodic table, including brackets, parentheses, and complex polyatomic formulas. Results are expressed in g/mol (grams per mole) · Da (Daltons) · amu (atomic mass units) — the three standard units of molecular mass.
This online molar mass calculator is trusted across every area of chemistry and life sciences: A-Level, AP Chemistry, IB Chemistry, JEE, and NEET molar mass problems, stoichiometry and limiting reagent calculations, solution preparation — calculating mass needed for a target molarity (M = mol/L), pharmaceutical drug synthesis and molecular formula verification, biochemistry — protein, peptide, and nucleic acid molecular weight calculation, mass spectrometry data interpretation, and polymer and materials science molecular weight distribution analysis. Common compound examples — H₂O (18.015 g/mol), NaCl (58.44 g/mol), C₆H₁₂O₆ glucose (180.16 g/mol), CaCO₃ (100.09 g/mol), H₂SO₄ (98.08 g/mol) — are all supported instantly. Trusted by chemistry students, laboratory chemists, pharmacists, biochemists, and research scientists worldwide for fast, accurate molar mass determination.
Molecular weight (also called molecular mass) is the total mass of all atoms present in a molecule. It is calculated by adding the atomic masses of each element in the chemical formula. Molecular weight is usually expressed in grams per mole (g/mol).
A molecular weight calculator helps determine the mass of a molecule quickly by summing the atomic weights of all atoms in the compound. This value is widely used in chemistry, biochemistry, pharmaceutical research, and chemical engineering.
Scientists rely on molecular weight to convert between grams and moles, balance chemical equations, prepare laboratory solutions, and determine reaction quantities. Accurate molecular weight calculations are essential for laboratory experiments and industrial chemical production.
For example, the molecular weight of water is obtained by adding the atomic masses of two hydrogen atoms and one oxygen atom.
The molecular weight of a compound is calculated by summing the atomic masses of all atoms in the molecule.
This formula is the basis of most molecular mass calculatorsused in chemistry education and laboratory work.
Consider the chemical formula for water: H₂O.
This means that one mole of water molecules has a mass of18.015 grams. Chemists use this value when converting between grams and moles during chemical calculations.
Molecular weight calculations are essential in stoichiometry, chemical reaction analysis, and laboratory solution preparation.
Below are the molecular weights of several commonly studied chemical compounds used in chemistry laboratories and industrial applications.
| Compound | Chemical Formula | Molecular Weight (g/mol) |
|---|---|---|
| Water | H₂O | 18.015 |
| Carbon Dioxide | CO₂ | 44.01 |
| Sodium Chloride | NaCl | 58.44 |
| Ammonia | NH₃ | 17.031 |
| Sulfuric Acid | H₂SO₄ | 98.079 |
Molecular weight calculations rely on atomic masses obtained from the periodic table of elements. These atomic weights represent the average mass of naturally occurring isotopes.
| Element | Symbol | Atomic Mass (g/mol) |
|---|---|---|
| Hydrogen | H | 1.008 |
| Carbon | C | 12.011 |
| Oxygen | O | 15.999 |
| Nitrogen | N | 14.007 |
| Sodium | Na | 22.990 |
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Molecular weight, also called molar mass, is the total mass of all atoms in a molecule. It is calculated by adding the atomic weights of each element in the chemical formula and is expressed in grams per mole (g/mol).
Chemical formulas are written using element symbols from the periodic table with subscripts to indicate the number of atoms. Examples include H2O, CO2, NaCl, and H2SO4.
In most chemistry contexts, molecular weight and molar mass are used interchangeably. Both represent the mass of one mole of a compound.
To calculate molar mass, multiply the atomic mass of each element by the number of atoms present in the formula and add the results together.
Currently the calculator supports simple chemical formulas without nested parentheses.
Molecular weight or molar mass is measured in grams per mole (g/mol).
Yes. The calculator works for organic compounds as long as the chemical formula uses standard periodic table elements.
Yes. This online molar mass calculator is completely free and works instantly in your web browser.
Molecular weight is calculated by summing the atomic masses of all atoms in the chemical formula. Each atomic mass is multiplied by the number of atoms present.
Atomic mass is the average mass of atoms of an element measured in atomic mass units (amu). It represents the weighted average of all naturally occurring isotopes.
A mole is a unit used to measure the amount of substance. One mole contains approximately 6.022 × 10²³ particles such as atoms, molecules, or ions.
Molar mass helps chemists convert between mass and moles, prepare solutions, perform stoichiometric calculations, and analyze chemical reactions.
Molar mass allows chemists to convert between grams and moles, which is essential for balancing chemical reactions and calculating reactant or product quantities.
Yes. For ionic compounds like NaCl, the molar mass is calculated by adding the atomic masses of the ions present in the chemical formula.
Atomic weight refers to the mass of a single element atom, while molecular weight refers to the total mass of all atoms in a molecule.
Subscripts in a chemical formula indicate the number of atoms present. Each subscript multiplies the atomic mass of that element in the molar mass calculation.
An empirical formula shows the simplest whole-number ratio of atoms in a compound, while the molecular formula shows the actual number of atoms.
A molecular formula shows the exact number of atoms of each element present in a molecule.
Atomic masses from the periodic table are used to determine the mass contribution of each element in a chemical formula.
Yes, as long as the chemical formula is valid and uses recognized periodic table elements.
Molar mass calculations are used in pharmaceuticals, chemical manufacturing, environmental science, biotechnology, and food chemistry.
Chemists calculate molecular weight to determine the mass of substances needed for reactions, solution preparation, and laboratory experiments.
Yes. Molar mass is one of the most fundamental calculations in chemistry laboratories for measuring reagents and preparing solutions.
Yes. This molecular weight calculator is useful for chemistry students, teachers, and researchers who need quick and accurate molar mass calculations.