molar-mass

Parse a chemical formula and get its molar mass in g/mol. No dependencies, CommonJS.

Supports nested groups ((NH4)2SO4), square brackets (K4[Fe(CN)6]), and dot-separated hydrates (CuSO4.5H2O or CuSO4·5H2O).

const { molarMass, massPercent, parseFormula } = require('molar-mass');

molarMass('H2O');            // 18.015
molarMass('C6H12O6');        // 180.156
molarMass('CuSO4.5H2O');     // 249.685

parseFormula('(NH4)2SO4');   // { N: 2, H: 8, S: 1, O: 4 }
massPercent('H2O');          // { H: 11.19..., O: 88.81... }

Atomic weights are the IUPAC 2021 conventional values, abridged. Elements 1–92 are covered. Isotopic masses and radioactive-element edge cases are out of scope — if you need those you probably want a proper cheminformatics toolkit.

License

ISC