Molecular Weight Calculator
A free online molecular weight calculator that parses any chemical formula — including nested parentheses like Ca(OH)₂ and hydrates like CuSO₄·5H₂O — to instantly compute molar mass, element composition percentages, and empirical formula. Features interactive composition charts and common compound presets, all calculated in your browser with no signup required.
Common Compounds
कोई सुझाव है?
नया टूल अनुरोध करें या सुधार सुझाएं — हमारे Slack समुदाय में शामिल हों!
What is a Molecular Weight Calculator?
A molecular weight calculator computes the molar mass of a chemical compound by summing the atomic masses of all atoms in its formula. Molar mass (g/mol) is essential for converting between mass and moles in stoichiometry, preparing solutions of specific molar concentrations, and determining reagent amounts for reactions. This tool parses formulas with nested parentheses, subscripts, and hydrate notation to provide accurate molecular weight, element composition percentages, and empirical formula.
How to Use This Calculator
- Enter a chemical formula using standard notation (e.g., C6H12O6 for glucose, Ca(OH)2 for calcium hydroxide)
- Or select a common compound from the preset buttons
- View the calculated molecular weight in g/mol
- Examine the element composition table showing atom count, mass contribution, and percentage for each element
- Copy the results for your lab notebook or report
Frequently Asked Questions
How do I enter a chemical formula with parentheses?
Use standard notation: Ca(OH)2 for calcium hydroxide, Fe2(SO4)3 for iron(III) sulfate. The calculator handles multiple levels of nesting correctly.
How do I enter hydrate formulas?
Use a dot (·) or period (.) to separate the hydrate: CuSO4·5H2O or CuSO4.5H2O. The calculator will parse both formats correctly.
What is the difference between molecular weight and molar mass?
Molecular weight (or molecular mass) is measured in atomic mass units (amu/Da) for a single molecule, while molar mass is measured in grams per mole (g/mol) for one mole of substance. Numerically, they are equivalent.
What atomic masses does this calculator use?
This calculator uses standard atomic weights from IUPAC 2021 recommendations, which reflect natural isotope abundances. For elements with variable isotope composition, the conventional atomic weight is used.