Molecular Weight from Formula
Client-side parser handling parentheses, subscripts.
Example
You enter
- Chemical formula NaCl
You get
- Molecular weight 58.44 g/mol
Checked against published worked examples from: IUPAC.
Details, formula, and sources
ScopeClient-side parser handling parentheses, subscripts, and water of hydration (CuSO4·5H2O or CuSO4.5H2O gives 249.68 g/mol). IUPAC standard atomic weights bundled.
Formula or tableMW = sum over elements (atomic_weight[element] * count). Formula parser supports parentheses and integer subscripts.
Source and editionIUPAC/CIAAW Abridged Standard Atomic Weights 2024 -- the Atomic Weights 2021 report with the 2024 revisions to gadolinium, lutetium and zirconium. Bundled in IUPAC_ATOMIC_WEIGHTS (data/lab/iupac-atomic-weights.json); of the three revised elements only zirconium is bundled, at its 2024 value of 91.222.
Free accessFree at iupac.org/publications/journals/pac/. Element-by-element values published in Pure and Applied Chemistry.
What governsVerify protocol against your lab's SOP before pipetting. A miscalculated dilution can ruin a run or a sample.
API field namesformula, molecular_weight
- Isotopic abundance natural terrestrial average per IUPACIUPAC 2021
- Hydrate notation dot (.) and middle-dot join molecules; a leading hydrate coefficient (CuSO4·5H2O) is not supported -- write it as CuSO4·(H2O)5convention