SMILES to InChI Converter
Turn a SMILES string into a standard InChI — the canonical, IUPAC-maintained identifier used by PubChem, ChEMBL and patent databases.
What is InChI?
InChI (International Chemical Identifier) is a standard, non-proprietary text identifier for chemical substances maintained by IUPAC. Unlike SMILES, which can be written in many equivalent ways for the same molecule, InChI is canonical: every valid representation of the same structure produces the same InChI string.
Why convert SMILES to InChI?
- Deduplication — two different SMILES for the same molecule give one InChI.
- Database lookup — PubChem, ChEMBL and Wikidata index compounds by InChI and InChIKey.
- Regulatory and patent filing — InChI is the IUPAC standard for structure registration.
- Stable keys — the 27-character InChIKey is a fixed-length hash you can use as a primary key.
Frequently asked questions
Does it preserve stereochemistry?
Yes. OpenBabel reads stereo information from the SMILES (@ and @@ markers) and encodes it in the InChI layer, so chiral centres are preserved.
Will I get the InChIKey too?
The output is InChI. To get the InChIKey, run the same input with the output format set to InChIKey, or use the property calculator.