⚖️ Grams to Moles Calculator
Convert sample mass into moles and particles to streamline stoichiometry, solution prep, and reagent planning.
Measured mass of the substance.
Look up or calculate from the chemical formula.
Controls how many meaningful digits appear in formatted results.
Moles
0.2775
Sub-mole quantity
Particles
1.6714e+23
Assumes Avogadro's constant: 6.022 x 10^23 particles per mole.
Molar Mass
18.015 g/mol
Provided or calculated for the compound.
For 5.00 g of material with molar mass 18.015 g/mol, you have approximately 0.2775 mol, equivalent to 1.6714e+23 particles.
How to Use This Calculator
Determine the molar mass
Calculate the molar mass from the chemical formula (sum of atomic masses) or pull it from a reference table.
Weigh the sample
Measure the sample mass in grams. For solutions, multiply concentration by volume to obtain grams of solute.
Enter mass and molar mass
Type the values into the calculator and optionally choose a significant figures setting for formatted output.
Record moles and particles
Use the computed amount to balance equations, scale reactions, or convert to other quantities like molarity.
Formula
n = m / M
N = n * N_A
n is the amount of substance in moles, m is sample mass in grams, M is molar mass (g/mol), and N_A is Avogadro's number (6.022 x 10^23 mol^-1).
Example
8.50 g of sodium chloride (M = 58.44 g/mol) contains n = 8.50 / 58.44 = 0.145 mol. That corresponds to 0.145 * 6.022 x 10^23 ≈ 8.74 x 10^22 formula units.
Full Description
Converting grams to moles is a core operation in stoichiometry. Because reagents react based on particle counts rather than mass, chemists translate weighed amounts into moles to compare relative quantities directly.
The calculator removes arithmetic overhead. Supply the measured mass and the compound's molar mass to obtain the corresponding moles and particle count. Adjustable significant figures help you match the precision of balances and molar mass references.
Use the results to scale reaction recipes, compute limiting reagents, back-calculate solution molarity, or cross-check lab notebook entries. The tool is equally useful for high school chemistry problems and professional laboratory workflows.
Frequently Asked Questions
Where do I find molar mass values?
Use periodic table data to sum atomic masses according to the chemical formula, or consult supplier documentation for complex reagents.
What if my sample is a hydrate?
Include water of crystallization in the molar mass. For example, CuSO4·5H2O has molar mass 249.68 g/mol, not 159.61 g/mol.
Can I convert back to grams from moles?
Yes. Multiply the moles by molar mass (m = n * M). This calculator focuses on grams to moles, but the same formula works in reverse.
How precise are the outputs?
Precision is controlled by the significant figures field. Enter a value that reflects the least precise input measurement.
Does temperature matter?
No. Grams and moles are independent of temperature. Temperature is relevant only when connecting moles to gas volumes via the ideal gas law.