Molecular Weight Calculator 2026 - Molar Mass Chemical Formula Tool

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Molecular Weight Calculator 2026 - Molar Mass Chemical Formula Tool

Compute exact molar mass (g/mol) and element mass percentages for chemical compounds like Water (H2O), Glucose (C6H12O6), Table Salt (NaCl), and Sulfuric Acid (H2SO4).

O (16.00) H H Molar Mass H2O 18.015 g/mol

Figure 1: Water molecule (H2O) molar mass composition model.

⚡ Interactive Chemical Molar Mass Calculator

Chemical Formula:
H2O
Compound Name:
Water
Total Molar Mass:
18.015 g/mol

2. What is Molecular Weight & Molar Mass?

Molar mass (molecular weight) is the physical property defined as the mass of a given chemical substance divided by the amount of substance (measured in moles). It is expressed in units of grams per mole (g/mol).

In analytical chemistry, pharmaceutical research, and industrial manufacturing, calculating exact molar mass is necessary for preparing laboratory buffer solutions, determining reaction stoichiometry, and converting between grams and moles.

3. Chemical Formula Summation Method

To calculate the molar mass of any compound, multiply each element's atomic mass by the number of atoms present in the chemical formula and sum the results:

Molar Mass (H2O) = (2 x Hydrogen Atomic Mass) + (1 x Oxygen Atomic Mass)
                 = (2 x 1.008 g/mol) + (1 x 15.999 g/mol)
                 = 2.016 + 15.999
                 = 18.015 g/mol

4. Step-by-Step Worked Numerical Example

Below is a complete stoichiometric breakdown for Water (H2O) and Glucose (C6H12O6):

Element Atomic Mass Atom Count Subtotal (g/mol)
Hydrogen (H) 1.008 g/mol 2 2.016 g/mol
Oxygen (O) 15.999 g/mol 1 15.999 g/mol
Total Water (H2O) Molar Mass 18.015 g/mol

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between molecular weight and molar mass?

Answer: Molecular weight is a dimensionless relative mass value (or in atomic mass units amu), while molar mass is the mass of one mole of substance expressed in grams per mole (g/mol). Numerically, they are identical.

Q2: How many molecules are in 18.015 grams of water?

Answer: Exactly one mole, which equals Avogadro's constant: 6.022 x 10^23 water molecules.

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