School calculator
Molar Mass Calculator
Molar mass in g/mol and mass percent of each element from any chemical formula.
Quick answer
How do you calculate molar mass?
Multiply each element's atomic mass by how many atoms it has, then add them. Water (H₂O) = 2 × 1.008 + 1 × 15.999 = 18.015 g/mol.
Molar mass = Σ (number of atoms × atomic mass) • moles = grams ÷ molar mass
⚡ Answer updates as you type · Enter = calculate · Esc = reset
| Element | Atoms | Atomic mass | Subtotal | Mass % |
|---|---|---|---|---|
| C | 6 | 12.011 | 72.066 | 40% |
| H | 12 | 1.008 | 12.096 | 6.71% |
| O | 6 | 15.999 | 95.994 | 53.28% |
- C: 6 × 12.011 = 72.066 g/mol
- H: 12 × 1.008 = 12.096 g/mol
- O: 6 × 15.999 = 95.994 g/mol
- Add them up: 72.066 + 12.096 + 95.994 = 180.156 g/mol
- So 1 mole of C6H12O6 weighs 180.156 grams. Moles = grams ÷ 180.156.
Type a chemical formula like H2O, NaCl, Ca(OH)2, or CuSO4·5H2O to get its molar mass in g/mol and percent of each element.
About this Molar Mass Calculator
The Molar Mass Calculator finds the molar mass (molecular weight) of any compound in g/mol. Type a chemical formula — including parentheses and hydrates like CuSO4·5H2O — to see each element's atoms, atomic mass, subtotal, and mass percent.
What you'll need
- • Chemical formula (e.g. NaCl, C6H12O6, Ca(OH)2)
How it works
- 1. Type the chemical formula.
- 2. Check capital letters (Co vs CO).
- 3. Read the molar mass in g/mol.
- 4. See the mass percent table.
- 5. Copy the steps for your lab report.
Worked example
Glucose C6H12O6 = 6(12.011) + 12(1.008) + 6(15.999) = 180.156 g/mol.
Related searches
Molar Mass Calculator FAQ
What is the Molar Mass Calculator?
The Molar Mass Calculator is a free online tool that helps you molar mass in g/mol and mass percent of each element from any chemical formula.
How do I use the Molar Mass Calculator?
Open the Molar Mass Calculator, enter the requested values, and review the instant estimate on the page.
Is the Molar Mass Calculator free?
Yes. The Molar Mass Calculator is free to use on Fast Online Calculator and does not require an account.
Is molar mass the same as molecular weight?
They have the same number. Molar mass is in g/mol; molecular weight is in atomic mass units (u).
How do I handle parentheses?
Multiply everything inside by the number after the bracket. Ca(OH)2 has 1 Ca, 2 O, and 2 H.
How do I convert grams to moles?
Divide grams by molar mass. 36 g of water ÷ 18.015 g/mol ≈ 2 moles.
What about hydrates?
Use a dot: CuSO4·5H2O (or CuSO4.5H2O) adds 5 water molecules.
Related calculators
School
Density Calculator
Solve D = m ÷ V for density, mass, or volume with unit conversion.
School
Scientific Notation Calculator
Convert to scientific notation and do math with steps.
School
Significant Figures Calculator
Count sig figs, round, and get scientific notation.
School
Percent Error Calculator
Percent error between measured and accepted values with steps.