Complex Compounds · Ionic Salts

Compound Molecular Weight Calculator

Calculate the molecular weight of complex chemical compounds including ionic salts, coordination compounds, hydrates, and multi-element formulas. This compound molecular weight calculator handles polyatomic groups in parentheses, bracket notation for coordination chemistry, and nested formula structures. Enter any compound formula to get the total molecular weight with full element breakdown.

118

Elements

∞

Compounds

100%

Free

分子量

支持所有118种元素 · IUPAC 2021 标准原子量

快速示例:

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在上方输入化学式以计算分子量

Live Analysis

Instant Compound Molecular Weight

Type any compound formula and see the molecular weight computed in real time.

This compound molecular weight calculator instantly decomposes complex formulas into their constituent elements. Polyatomic groups like (SO₄), (PO₄), (NO₃), and (OH) are resolved by multiplying the inner atom counts by the outer subscript.

For Al₂(SO₄)₃: the calculator identifies Al:2, then resolves (SO₄)₃ as S:3 and O:12. The total molecular weight is Al: 2×26.98 + S: 3×32.07 + O: 12×16.00 = 342.15 g/mol.

The same engine handles ionic compounds, covalent compounds, and mixed-type compounds with equal accuracy.

Compound Formula

Common Elements

Elements in Compound Formulas

Elements commonly found in chemical compounds and their atomic weights.

Chemical compounds combine elements from across the periodic table. Ionic compounds typically pair metals (Na, K, Ca, Fe) with nonmetals or polyatomic anions (Cl, SO₄, PO₄, CO₃).

The molecular weight of a compound depends on which elements are present and their atom counts. Heavy elements like lead (207.20 g/mol) and barium (137.33 g/mol) contribute significantly to compound molecular weight.

Explore the element cards below to see atomic weights of elements commonly found in chemical compounds.

Lithium

6.9410

Sodium

22.9898

Aluminium

26.9815

Potassium

39.0983

Calcium

40.0780

Manganese

54.9380

Iron

55.8450

Copper

63.5460

Zinc

65.3800

Silver

107.8682

Barium

137.3270

Lead

207.2000

How to Use

How to Find Compound Molecular Weight

Three steps to calculate the molecular weight of any compound.

Enter Your Compound Formula

Type the chemical formula of your compound. For multi-element compounds with polyatomic groups, use parentheses: Ca₃(PO₄)₂, Al₂(SO₄)₃, Fe₃(CO)₁₂. The calculator handles ionic compounds, coordination compounds, and complex salts with nested brackets and braces.

Ca₃(PO₄)₂

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Ca × 3P × 2O × 8

Examples

Compound Molecular Weight Examples

Click any compound to load it and see the full weight breakdown.

FAQ

Compound Molecular Weight FAQ

Questions about calculating molecular weight for complex compounds and ionic salts.

What is compound molecular weight?

Compound molecular weight is the total mass of all atoms in a single unit of a chemical compound, measured in grams per mole (g/mol) or Daltons (Da).

How do you calculate molecular weight of a complex compound?

For complex compounds with polyatomic groups, first expand the parentheses: Ca₃(PO₄)₂ = Ca₃P₂O₈.

What is the difference between molecular weight and formula weight for ionic compounds?

For ionic compounds like NaCl or CaCO₃, 'formula weight' is technically more correct because these compounds form crystal lattices rather than discrete molecules.

How do you handle compounds with water of crystallization?

For hydrated compounds like CuSO₄·5H₂O, enter the complete formula using parentheses: CuSO₄(H₂O)₅ or equivalently CuH₁₀SO₉.

Can I calculate molecular weight of a salt?

Yes.

What about double salts and complex compounds?

For double salts, enter the combined formula.

How accurate is this for pharmaceutical compounds?

This calculator provides 4-decimal-place accuracy using IUPAC 2021 standard atomic weights, matching the precision used in pharmaceutical reference standards from the United States Pharmacopeia (USP) and the British Pharmacopoeia (BP).