Molar Mass Calculator
Molar mass of common compounds and mole conversion.
Enter your values
Enter the sample mass in g.
Enter the molar mass in g/mol (water default).
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Moles
- 0.9989 mol
- Number of molecules
- 6.015e+23
- Molar mass used
- 18.02 g/mol
Quick answer
Moles = mass (g) / molar mass (g/mol).
n = m / M
At a glance
| What it does | Molar mass of common compounds and mole conversion. |
|---|---|
| Category | Science |
| Inputs needed | Sample mass, Molar mass |
| Main output | Moles |
| Formula | n = m / M |
| Cost | Free — no sign-up, no download |
How to use the Molar Mass Calculator
- 1Enter the mass of your sample in grams.
- 2Enter the compound's molar mass (sum of atomic masses, or look it up on the periodic table).
- 3Read the number of moles and molecules present.
Inputs explained
- Sample mass(g)
- Enter the sample mass in g.
- Molar mass(g/mol (water default))
- Enter the molar mass in g/mol (water default).
Worked example
Using the values the calculator loads with:
Inputs
- Sample mass18 g
- Molar mass18.02 g/mol (water default)
Results
- Moles0.9989 mol
- Number of molecules6.015e+23
- Molar mass used18.02 g/mol
Frequently asked questions
How do I find molar mass myself?
Add up the atomic masses of every atom in the formula, e.g. H2O = 2(1.008) + 16.00 = 18.02 g/mol.
What is Avogadro's number used for here?
It converts moles to the actual number of molecules or atoms present, 6.022e23 per mole.
What do I need to enter into the Molar Mass Calculator?
Just 2 values: sample mass, molar mass. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Molar Mass Calculator work out the answer?
Moles = mass (g) / molar mass (g/mol). It applies the formula n = m / M and shows the working so you can check each step by hand.
Is the Molar Mass Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.