Convert mass to moles instantly with our chemistry calculator.
Ever stared at a chemistry problem, wondering how to convert grams into moles? You’re not alone. Understanding the relationship between mass and moles is fundamental to chemistry, yet it trips up students and professionals alike.
Here’s the good news: converting grams to moles is actually straightforward once you know the molar mass of your substance.
Our converter eliminates the guesswork by providing instant, accurate conversions for elements and common compounds. Just enter your mass, select your substance, and watch the math happen automatically.
Grams to Moles Converter | Free Chemistry Calculator
12.011g/mol
g
Amount of substance
mol
Number of moles
Conversion Result
2.000
moles
24 g ÷ 12.011 g/mol = 2.000 mol
🔢
Molecules/Atoms
1.20 × 1024
particles
⚖️
Molar Mass
12.011
g/mol
📊
Mass per Mole
12.011
grams
🧮
Avogadro’s Number
6.022 × 1023
/mol
📝 Conversion Formulas
Moles = Mass (g) ÷ Molar Mass (g/mol) | Mass (g) = Moles × Molar Mass (g/mol)
📖 How to Use This Converter
1
Select Type
Choose Element, Compound, or Custom input
2
Pick Substance
Select from list or enter molar mass
3
Enter Mass
Input the mass in grams
4
Get Results
View moles, particles, and more
🔬 Understanding Moles and Molar Mass
⚛️ What is a Mole?
A mole is the SI unit for “amount of substance.” It represents exactly 6.02214076 × 10²³ particles — atoms, molecules, or ions. Think of it as a “chemist’s dozen.”
1 mol = 6.022 × 10²³ particles
⚖️ What is Molar Mass?
Molar mass is the mass of one mole of a substance in grams. For elements, it equals the atomic mass on the periodic table. For compounds, add up all atomic masses.
H₂O = 2(1.008) + 16.00 = 18.016 g/mol
🧮 The Conversion
To convert grams to moles, divide the mass by molar mass. To convert moles to grams, multiply moles by molar mass. It’s that simple!
Moles = Grams ÷ Molar Mass
🔢 Avogadro’s Number
Named after Amedeo Avogadro, this constant (Nₐ = 6.022 × 10²³) connects the macroscopic world (grams) to the atomic world (individual particles).
Remember: molar mass numerically equals atomic/molecular mass
Practice with different units (mg, kg) by converting to grams first
⚠️ Common Mistakes
Avoid these frequent errors:
Forgetting to multiply atomic mass by subscripts in formulas
Confusing molar mass with atomic number
Using wrong units (kg instead of g)
Rounding too early in calculations
🔬 Real-World Uses
Mole calculations are essential in:
Pharmaceutical drug dosing
Industrial chemical production
Environmental testing
Food science and nutrition
Medical laboratory analysis
❓ Frequently Asked Questions
What is the formula for converting grams to moles?
The formula is: Moles = Mass (grams) ÷ Molar Mass (g/mol). For example, to find moles of 36 grams of water (H₂O): 36 g ÷ 18.015 g/mol = 2.0 moles.
How do I find the molar mass of a compound?
Add up the atomic masses of all atoms in the molecular formula. For H₂O: 2 hydrogen atoms (2 × 1.008 = 2.016) + 1 oxygen atom (16.00) = 18.016 g/mol. For NaCl: 22.99 (Na) + 35.45 (Cl) = 58.44 g/mol.
What is Avogadro’s number and why is it important?
Avogadro’s number is 6.02214076 × 10²³, representing the number of particles (atoms, molecules, ions) in one mole. It’s the bridge between the atomic scale and the macroscopic scale, allowing chemists to count atoms by weighing substances.
How do I convert moles back to grams?
Multiply moles by molar mass: Mass (g) = Moles × Molar Mass (g/mol). For example, 3 moles of NaCl: 3 mol × 58.44 g/mol = 175.32 grams.
Why is the mole concept important in chemistry?
Chemical reactions occur in fixed ratios of atoms and molecules, not fixed masses. The mole allows chemists to “count” particles by weighing them, making stoichiometry calculations and balanced equations possible.
What’s the difference between molar mass and molecular weight?
They’re numerically equivalent but technically different. Molar mass has units (g/mol), while molecular weight (relative molecular mass) is dimensionless. In practice, they’re often used interchangeably.
How many molecules are in one mole?
Exactly 6.02214076 × 10²³ molecules. This is true for any substance — one mole of water and one mole of glucose both contain the same number of molecules, even though they have very different masses.
Can I convert grams to moles for a mixture?
Not directly. Mixtures don’t have a single molar mass. You need to know the composition and convert each component separately, or use an average molar mass if the mixture composition is known.
How do I calculate moles of atoms in a compound?
First find moles of the compound, then multiply by the subscript of that atom in the formula. For 1 mole of H₂O, there are 2 moles of H atoms and 1 mole of O atoms. For 0.5 moles of H₂O, there are 1 mole of H atoms and 0.5 moles of O atoms.
What’s the relationship between moles and molarity?
Molarity (M) is concentration in moles per liter of solution: M = moles of solute ÷ liters of solution. If you have 2 moles of NaCl dissolved in 0.5 liters of water, the molarity is 2 ÷ 0.5 = 4 M (molar).