Moles to Grams Calculator
Enter formula to auto-calculate molar mass. Use uppercase for element symbols.
Molar mass in grams per mole. Auto-filled when you select a compound or enter a formula.
Enter Your Values
Select a compound or enter a chemical formula and molar mass, then input the number of moles (or mass) to see the conversion result.
How to Use This Calculator
Choose Conversion Direction
Click 'Moles → Grams' to find the mass from a known number of moles, or 'Grams → Moles' to find the moles from a known mass. The input fields update automatically to match your selection.
Enter Your Substance
Select a pre-populated compound from the dropdown (e.g., Water, Glucose, NaCl), or type a chemical formula such as H2O or KMnO4. The molar mass field fills automatically. Alternatively, enter the molar mass directly in the field.
Input the Known Quantity
Enter the number of moles (with optional unit: mol, mmol, µmol, nmol, pmol, fmol) or the mass (with optional unit: g, mg, kg, µg). Use the precision slider to set the number of significant figures in the result.
Read Your Results
The answer appears instantly in the results panel. Review the step-by-step solution showing the formula and substituted values, the number of molecules via Avogadro's number, and the elemental composition bar chart (when a formula is provided).
Frequently Asked Questions
How do I convert moles to grams?
To convert moles to grams, multiply the number of moles by the molar mass of the substance: mass (g) = moles × molar mass (g/mol). For example, to find the mass of 2 moles of water (H₂O, molar mass = 18.015 g/mol): mass = 2 × 18.015 = 36.030 g. The molar mass can be found on the periodic table by summing the atomic masses of all atoms in the compound's formula. This calculator does this automatically when you enter a chemical formula or select from the compound dropdown.
How do I convert grams to moles?
To convert grams to moles, divide the mass by the molar mass: moles = mass (g) ÷ molar mass (g/mol). For example, 58.44 g of sodium chloride (NaCl, molar mass = 58.443 g/mol) contains 58.44 ÷ 58.443 ≈ 1.000 mol. Switch the calculator to 'Grams → Moles' mode, enter the mass with its unit, and the moles result appears instantly. This is the reverse operation of the moles-to-grams calculation and uses the same molar mass value.
What is molar mass and how is it calculated?
Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in one formula unit of the compound. Atomic masses are listed on the periodic table in atomic mass units (u), which are numerically equal to g/mol. For glucose (C₆H₁₂O₆): 6(12.011) + 12(1.008) + 6(15.999) = 72.066 + 12.096 + 95.994 = 180.156 g/mol. This calculator's built-in formula parser does this calculation automatically for any standard chemical formula.
What is Avogadro's number and why does it appear here?
Avogadro's number (Nₐ = 6.02214076 × 10²³ mol⁻¹) is the number of elementary particles in exactly one mole of a substance. It was named after the Italian scientist Amedeo Avogadro. This number connects the macroscopic world (grams you can measure) with the microscopic world (individual atoms and molecules). This calculator multiplies your moles result by Avogadro's number to show how many actual molecules are present in your sample — a useful quantity for understanding reaction rates, concentration, and spectroscopy experiments.
Can I use this calculator for non-standard units like mmol or µg?
Yes. The calculator supports six mole units: mol, mmol (millimoles, 10⁻³ mol), µmol (micromoles, 10⁻⁶ mol), nmol (nanomoles, 10⁻⁹ mol), pmol (picomoles, 10⁻¹² mol), and fmol (femtomoles, 10⁻¹⁵ mol). For mass, it supports g, mg, kg, and µg. Select the appropriate unit from the dropdown next to the input field. All conversions are internally computed in base units (mol and grams) to ensure accuracy regardless of the scale chosen.
Why does my chemical formula give an error?
The formula parser recognizes standard element symbols (one or two letters, first capitalized) followed by optional subscript numbers, with support for parentheses and multipliers. Common issues include: using all-lowercase letters (write 'H2O' not 'h2o'), using element symbols not in the standard periodic table, entering formulas for hydrates with a dot (e.g., CuSO4·5H2O — enter these compounds' molar mass manually instead), or including special characters. If the parser fails, enter the molar mass directly in the molar mass field — the conversion will work the same way.