Molecular Formula Calculator
Determine the molecular formula and empirical formula of any chemical compound from its elemental composition, mass data, or compound name.
| Element | Atomic Mass | Atoms | Total | % |
|---|
Quick Examples
Click any compound to calculate its molecular weight instantly.
How to Use the Molecular Formula Calculator
To find the molecular formula of a compound, enter its chemical formula or compound name into the input field and click "Calculate." The calculator identifies each element, counts the atoms, and returns the complete molecular formula with associated molar mass.
Follow these 5 steps to determine a molecular formula:
- Enter the chemical formula using standard notation. Write element symbols with an uppercase first letter and lowercase second letter (e.g., "Fe" for iron, "Ca" for calcium). Place subscript numbers directly after each element.
- For compounds with polyatomic groups, use parentheses followed by subscripts. Enter calcium hydroxide as "Ca(OH)2" and aluminum sulfate as "Al2(SO4)3".
- Press "Calculate" or hit Enter. The calculator parses the formula, resolves parenthetical groups, and identifies every element and its atom count.
- Review the molecular formula displayed in the results. The element tiles show each atom's symbol, atomic number, and mass contribution.
- Check the breakdown table for exact atomic masses, atom counts, subtotals, and percentage composition by mass for each element.
The percentage composition output is particularly useful for reverse calculations: confirming whether experimental composition data matches a proposed molecular formula.
How the Molecular Formula Calculator Works
The molecular formula calculator works by parsing a chemical formula string into its component elements and their atom counts. It applies standard chemical notation rules—element symbols, subscripts, parentheses, and hydrate dots—to build an accurate atom inventory.
The relationship between empirical formula and molecular formula follows this equation:
When you enter a known formula like C₆H₁₂O₆ (glucose), the calculator confirms that carbon makes up 40.00%, hydrogen 6.71%, and oxygen 53.29% of the total mass (180.156 g/mol). These percentages match the standard elemental analysis results for glucose, verifying the molecular formula.
The calculator supports formulas ranging from simple diatomic molecules like O₂ to complex coordination compounds and hydrated salts. It handles nested parentheses such as Ca₃(PO₄)₂ and multi-group hydrates like FeSO₄·7H₂O.
Common Compound Molecular Weights
Reference table of frequently searched chemical compounds.
| Chemical Formula | Compound Name | Molecular Weight |
|---|---|---|
| H₂O | Water | 18.015 g/mol |
| CO₂ | Carbon Dioxide | 44.009 g/mol |
| NaCl | Sodium Chloride | 58.443 g/mol |
| NH₃ | Ammonia | 17.031 g/mol |
| CH₄ | Methane | 16.043 g/mol |
| H₂SO₄ | Sulfuric Acid | 98.077 g/mol |
| CaCO₃ | Calcium Carbonate | 100.086 g/mol |
| C₆H₁₂O₆ | Glucose | 180.156 g/mol |
| C₂H₅OH | Ethanol | 46.069 g/mol |
| HCl | Hydrochloric Acid | 36.461 g/mol |
| NaOH | Sodium Hydroxide | 39.997 g/mol |
| Ca(OH)₂ | Calcium Hydroxide | 74.092 g/mol |
| HNO₃ | Nitric Acid | 63.012 g/mol |
| KMnO₄ | Potassium Permanganate | 158.032 g/mol |
| CuSO₄ | Copper(II) Sulfate | 159.607 g/mol |
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Molecular Formula Calculator FAQs and Common Questions
Answers to common questions about finding molecular formulas, empirical formulas, and interpreting composition data.