SMILES to Molecular Weight
Get the molecular formula and molar mass from a SMILES string.
Learn more
What it does
The SMILES to molecular weight tool converts a SMILES string into its molecular formula and molar mass. It is used by cheminformatics workers, medicinal chemists, and students who need a quick formula and mass from a structure drawn as text.
How it works
SMILES is a line notation for chemical structures where atoms are written by element symbol, branches use parentheses, ring closures use matched digits, and aromatic atoms are written in lower case. The tool parses the string into its atoms, estimates implicit hydrogens from standard valence rules, and sums the IUPAC atomic weights to give the molecular formula and molar mass. It covers the common organic subset (B, C, N, O, P, S, F, Cl, Br, I), aromatic rings, branches, ring closures, and simple bracketed atoms such as charges.
Worked example
The SMILES CCO is ethanol. It has 2 carbons, 6 hydrogens (including implicit hydrogens), and 1 oxygen: formula C2H6O. The molar mass is 2×12.011 + 6×1.008 + 15.999 = 46.07 g/mol. Acetic acid CC(=O)O gives C2H4O2 with mass 60.05 g/mol. Benzene c1ccccc1 gives C6H6 with mass 78.11 g/mol.
When to use it
Use it to get the molar mass of a compound when you only have its SMILES from a database. Use it to check the molecular formula before ordering or synthesizing a molecule. Use it in teaching to connect a drawn structure with its formula and mass.
FAQ
- What is a SMILES string?
- SMILES is a compact text notation for a molecule. Atoms are written by symbol, branches in parentheses, rings with matching digits, and aromatic atoms in lower case, for example CCO for ethanol.
- How is the molar mass computed from SMILES?
- The tool counts each atom in the structure, adds implicit hydrogens from valence, and sums the atomic weights of all atoms using IUPAC values to give the molar mass.
- Are implicit hydrogens included in the mass?
- Yes. Hydrogens not written in the SMILES are estimated from each atom's valence and are included in both the molecular formula and the molar mass.
- Which elements does the converter support?
- It supports the common organic subset: B, C, N, O, P, S, F, Cl, Br, and I, including aromatic rings, branches, ring closures, and simple bracketed atoms with charges.