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Calculated Molecular Weight

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Molecular Weight Calculator

Calculate molecular weight from chemical formulas. Perfect for chemistry students and laboratory work.

What is Molecular Weight Calculator?

Molecular Weight Calculator is a free online tool that calculates the molecular weight (molar mass) of chemical compounds from their formulas. It allows you to input chemical formulas or add elements manually and calculates the total molecular weight. Perfect for chemistry students, researchers, and laboratory work.

How to Use Molecular Weight Calculator

  1. Enter a chemical formula (e.g., H2O, C6H12O6) and click "Parse" to automatically extract elements
  2. Or manually add elements by selecting from the periodic table and specifying counts
  3. The molecular weight calculation happens automatically as you add elements
  4. Adjust element counts by editing the input fields
  5. Remove elements using the minus button
  6. Copy the result using the copy button
  7. Use Clear to reset all values

Molecular Weight Formula

MW = Σ(Atomic Weight × Count)
Molecular Weight = Sum of (Atomic Weight × Number of atoms)

Example: H2O

  • • H: 1.008 × 2 = 2.016
  • • O: 15.999 × 1 = 15.999
  • • Total: 2.016 + 15.999 = 18.015 g/mol

Supported Elements

  • • Common elements: H, C, N, O, S, P, Cl, etc.
  • • Metals: Na, Mg, Al, K, Ca, Fe, Cu, Zn, Ag, Au, Hg, Pb
  • • Noble gases: He, Ne, Ar
  • • Units: g/mol (grams per mole)

Frequently Asked Questions

What's the difference between molecular weight and molar mass?

Molecular weight and molar mass are essentially the same thing - the mass of one mole of a substance. Both are expressed in g/mol and have the same numerical value.

How do I enter complex formulas?

Use the "Parse" function for simple formulas like H2O or C6H12O6. For complex formulas with parentheses or special characters, add elements manually using the periodic table selector.

What if an element is not in the periodic table?

The calculator includes the most common elements. If you need additional elements, you can add them manually by entering the atomic weight directly.

How accurate are the atomic weights?

The atomic weights used are the standard values from the periodic table, accurate to 3-4 decimal places for most practical chemistry applications.

Is my data secure?

Yes, all calculations happen locally in your browser. Your data never leaves your device.

Can I use this offline?

Yes, once loaded, the calculator works completely offline in your browser.