Molar mass is the mass of one mole of a substance in grams per mole (g/mol). It is calculated as M = Σ(n × atomic mass) where n is the number of atoms of each element.

What is the difference between molar mass and molecular weight?

They represent the same value. Molar mass uses g/mol; molecular weight traditionally uses atomic mass units (amu). Both are essential for stoichiometry.

How do I enter hydrates in the formula?

Use CuSO4·5H2O or CuSO4.5H2O. The dot or middle dot indicates water of hydration. The calculator will include the water mass in the total.

How is percent composition calculated?

Percent composition = (element mass in 1 mole / total molar mass) × 100. The sum of all element percentages equals 100%.

How do I convert mass to moles?

Use n = m/M where n is moles, m is mass in grams, and M is molar mass in g/mol. For example, 18 g water = 18/18.015 ≈ 1 mole.

What is Avogadro's number?

6.022×10²³ particles per mole. One mole of any substance contains this many atoms, molecules, or formula units.

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CHEMISTRYStoichiometryChemistry Calculator

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Molar Mass

Calculate the molar mass of any chemical compound from its molecular formula. Includes percent composition, mass-mole conversions, and element breakdown analysis.

Run the CalculationExplore molecular and chemical calculations

⚗️Molar Mass CalculatorM = Σ(n × A) | n = m/M

Compact Examples

💧 Water (H₂O)

The universal solvent - essential for all known life forms

🍬 Glucose (C₆H₁₂O₆)

Simple sugar - primary energy source for cells

🧂 Sodium Chloride (NaCl)

Common table salt - essential electrolyte

⚗️ Sulfuric Acid (H₂SO₄)

Industrial workhorse - most produced chemical

☕ Caffeine (C₈H₁₀N₄O₂)

Central nervous system stimulant found in coffee

💊 Aspirin (C₉H₈O₄)

Common pain reliever and anti-inflammatory

Inputs

Input Mode

Chemical FormulaEnter formula using element symbols and subscript numbers

Number of MolesFor mass calculations

⚠️For educational and informational purposes only. Verify with a qualified professional.

📋 Key Takeaways

• M = Σ(n × A) | Sum atomic masses × atom counts
• n = m/M | Moles from mass; m = n × M
• % = (element mass / M) × 100 | Percent composition
• 1 mol = 6.022×10²³ | Avogadro's number

Did You Know?

💧

H₂O = 18.015 g/mol; NaCl = 58.44 g/mol.

Source: IUPAC

🍬

Glucose C₆H₁₂O₆ = 180.16 g/mol.

Source: Biochemistry

⚛️

Molar mass = molecular weight in g/mol.

Source: Stoichiometry

📐

Use subscripts: H2O, C6H12O6 (no special chars).

Source: Parser

🧪

Essential for stoichiometry and solution prep.

Source: Lab

📊

Percent composition sums to 100%.

Source: Analytical

How the Molar Mass Calculator Works

Enter formula (e.g. H2O, NaCl) or select elements. Parser sums n × atomic mass for each element.

Formula

M = Σ(n × A)

Moles

n = m/M; m = n × M

Expert Tips

Subscripts

H2O not H₂O; C6H12O6.

Parentheses

Ca(OH)2, (NH4)2SO4.

Hydrates

CuSO4·5H2O.

IUPAC

Uses standard atomic weights.

Common Compounds (g/mol)

Compound	M (g/mol)
H₂O	18.015
NaCl	58.44
C₆H₁₂O₆	180.16
CO₂	44.01

FAQ

What is molar mass?

Mass of 1 mole in g/mol. M = Σ(n × atomic mass).

Molar mass vs molecular weight?

Same value; g/mol vs amu.

How to enter hydrates?

CuSO4·5H2O or CuSO4.5H2O.

Percent composition?

% = (element mass in 1 mol / M) × 100.

Moles from mass?

n = m / M.

Avogadro number?

6.022×10²³ particles per mole.

Key Numbers

6.022×10²³

Avogadro

18.015

H₂O (g/mol)

58.44

NaCl (g/mol)

180.16

Glucose (g/mol)

📚 Official Sources

IUPAC Atomic Weights ↗

IUPAC standard atomic weights

NIST Chemistry WebBook ↗

Molar mass and thermodynamic data

CIAAW Tables ↗

Commission on Isotopic Abundances and Atomic Weights

⚠️ Disclaimer: Uses IUPAC atomic weights. Consult CIAAW and NIST for precise data.

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