Molar Mass Calculator

Name: Molar Mass Calculator
Author: CalculatorBolt

Calculate the molar mass (molecular weight) of a chemical compound from its formula. Enter the chemical formula and number of moles to get the molar mass in g/mol, total mass, and elemental composition percentages. Informational only—verify with a chemical reference. Explore more tools on free calculators on CalculatorBolt.

Calculator

Chemical Formula

Enter chemical formula using standard notation

Number of Moles

Amount in moles

Molar Mass

Total Mass

Import JSON

How it works

Molar Mass = Σ (Atomic Weight × Count of Each Element)

We parse the chemical formula to identify each element and its count, then sum the atomic weights of all atoms multiplied by their counts. The result is displayed in grams per mole (g/mol).

Total Mass = Molar Mass × Number of Moles

Elemental Composition % = (Element Mass / Total Molar Mass) × 100

Inputs explained

Chemical Formula: Enter using standard notation (e.g., H2O, C6H12O6, Ca(OH)2). Use capital letters for element symbols and numbers for atom counts.
Number of Moles: The amount of substance to calculate the total mass for. Defaults to 1 mole.

Example

Calculate molar mass of Water (H₂O):

2 × Hydrogen (H): 2 × 1.008 = 2.016 g/mol
1 × Oxygen (O): 1 × 15.999 = 15.999 g/mol
Total Molar Mass = 2.016 + 15.999 = 18.015 g/mol

For 1 mole of water, total mass = 18.015 g

Elemental Composition:

H: (2.016 / 18.015) × 100 = 11.19%
O: (15.999 / 18.015) × 100 = 88.81%

Tips & notes

Use standard chemical notation with capital letters for elements (H, O, C, etc.) and lowercase for second letters (Cl, Ca, etc.).
Parentheses indicate groups of atoms that are multiplied by the subscript after them: Ca(OH)2 = Ca + 2×O + 2×H.
This calculator uses standard IUPAC atomic weights based on naturally occurring isotopic abundances.
Common formulas: Water (H2O), Glucose (C6H12O6), Table Salt (NaCl), Sulfuric Acid (H2SO4), Calcium Carbonate (CaCO3).
For ions, omit the charge in the formula (e.g., use SO4 not SO4²⁻).
The calculator automatically handles elements from hydrogen through the periodic table.

Common Compound Examples

Compound	Formula	Molar Mass (g/mol)
Water	H₂O	18.015
Carbon Dioxide	CO₂	44.009
Glucose	C₆H₁₂O₆	180.156
Sodium Chloride	NaCl	58.440
Sulfuric Acid	H₂SO₄	98.078
Calcium Hydroxide	Ca(OH)₂	74.093
Ammonia	NH₃	17.031
Methane	CH₄	16.042

FAQs

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It equals the sum of the atomic weights of all atoms in the chemical formula.

Sum the atomic weights of all atoms in the chemical formula. For example, H2O has 2 hydrogen atoms (2 × 1.008) + 1 oxygen atom (1 × 15.999) = 18.015 g/mol.

Yes, this calculator works for any chemical formula, including organic compounds like glucose (C6H12O6), complex inorganic compounds, and molecules with parentheses.

No. Everything runs in your browser. Use Export or Share Link to save your calculation.

Standard atomic weights are average atomic masses based on naturally occurring isotopic abundances, as defined by IUPAC (International Union of Pure and Applied Chemistry).

Yes, enter the number of moles and the calculator will compute the total mass (molar mass × moles) in grams.

Use standard chemical notation: Ca(OH)2, Al2(SO4)3, etc. The calculator parses parentheses to multiply groups of atoms.

Elemental composition shows the percentage by mass of each element in the compound. It's calculated as (element mass / total molar mass) × 100%.

Disclaimer

Informational tool based on standard IUPAC atomic weights. For precise scientific work, consult a chemical reference or database. Atomic weights may vary slightly depending on isotopic composition and measurement standards.