Mole Calculator
Enter a chemical formula and mass or amount of substance. Find molar mass, moles and particle count with an element-by-element breakdown.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Add each element’s standard atomic weight multiplied by its atom count to obtain molar mass. Divide mass in grams by molar mass in g/mol to obtain moles. Multiply moles by the exact Avogadro constant to count the specified elementary entities.
M = Σ(atom count × atomic weight); n = m/M; N = n × 6.02214076 × 10²³
Worked example
For H₂O, M = 2 × 1.008 + 15.999 = 18.015 g/mol using the stored abridged weights. A mass of 18.015 g represents approximately 1 mol and 6.02214076 × 10²³ molecules.
Assumptions and input details
The stored CIAAW 2024 abridged standard-weight table covers 84 elements with standard atomic weights. Values are approximate for normal terrestrial materials; isotope-specific masses and uncertainty propagation are not calculated. Parentheses and hydrates such as CuSO4·5H2O are supported. Charges, isotope notation and reaction equations are not. Particle count refers to molecules, atoms or formula units as appropriate.
References: CIAAW abridged atomic weights · NIST: definition of the mole
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
The 19 mass definitions distinguish avoirdupois and troy measures, metric and regional measures. Japanese kin is 600 g; mainland Chinese shijin is 500 g.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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