Mol Weight Calculator

Need to calculate the molecular weight of a compound or determine how many moles are in a given mass? This easy-to-use Mol Weight Calculator helps students, chemists, and educators solve chemical calculations with accuracy and speed.

Molecular Weight Calculator

Use uppercase for first letter of element (H, O, C, Na, Cl, etc.)
0.00 g/mol

Elements Breakdown:

🧪 How to Use

  1. Enter Chemical Formula
    e.g., H₂O, C₆H₁₂O₆, NaCl, or Ca(OH)₂
    (Supports parentheses for groups like Mg(OH)₂)
  2. Enter Amount in Grams (optional)
    This step lets you calculate the number of moles based on the molecular weight.
  3. Click “Calculate”
  4. View:
    • ✅ Molecular Weight in g/mol
    • ✅ Moles (if grams entered)
  5. Use “Reset” to clear all fields and start again.

❓ Frequently Asked Questions (FAQs)

1. What is molecular weight?

Molecular weight is the sum of atomic weights of all atoms in a molecule, expressed in grams per mole (g/mol).

2. What is a mole?

A mole is a standard scientific unit for measuring large quantities of very small entities like atoms, molecules, or ions — defined as 6.022 × 10²³ particles.

3. Can I use formulas with parentheses like Ca(OH)₂?

Yes! The calculator supports parentheses and applies proper multiplication to grouped atoms.

4. What if I input an unknown element?

The tool will alert you if an element is not recognized or if the formula syntax is incorrect.

5. Can I calculate moles without entering grams?

Yes, but in that case, only molecular weight is shown. To get moles, enter the mass in grams.

6. Does it support complex organic compounds?

Yes, for most cases like:

  • Glucose: C6H12O6
  • Ethanol: C2H5OH
  • Aspirin: C9H8O4

Nested or advanced bracket logic (e.g. hydrate forms) may require simpler input.

7. How accurate are the atomic weights used?

Atomic weights are based on standard periodic table values and are accurate to four decimal places for precision.

8. Can I input formulas in lowercase?

No. Element symbols must start with uppercase letters, followed by optional lowercase letters (e.g. “Na”, “Cl”, not “na” or “cl”).

9. What units should I use for weight?

The calculator uses:

  • Grams (g) for weight input
  • Grams per mole (g/mol) for molecular weight
  • Mol for calculated moles

10. Do I need an internet connection?

No, it works fully offline if embedded in an app or local HTML environment.

🎓 Great For:

  • Chemistry students and teachers
  • Lab professionals
  • Engineering calculations
  • Competitive exam prep (e.g. MCAT, SAT Subject Tests, etc.)