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What is SMILES to InChI?
SMILES to InChI converts SMILES strings into InChI (International Chemical Identifier) strings using RDKit. InChI was developed by IUPAC and NIST as a canonical, non-proprietary chemical identifier. Unlike SMILES — which can represent the same molecule in multiple valid ways — InChI is fully canonical, meaning any two valid SMILES strings for the same molecule will always produce an identical InChI string. This makes InChI valuable for deduplication, database registration, and interoperability with systems that use InChI as a primary key, including ChEMBL and InChIKey-based lookup services.
InChIKey, a fixed-length 27-character hash derived from a full InChI string, is widely used for web searches and database lookups. This tool produces full InChI strings; InChIKey generation is a separate downstream step.
How to use SMILES to InChI online
The tool accepts SMILES directly in the browser, supports file upload, and can also retrieve structures from PubChem by compound name or CID. Up to 10 entries are processed per job.
Input
| Option | Details |
|---|---|
| SMILES strings | One SMILES per line, or name<TAB>SMILES pairs for named entries |
| File upload | .txt, .csv, .tsv, .smi, .smiles files |
| PubChem fetch | Compound names or CIDs for batch structure retrieval |
Output
| File | Description |
|---|---|
| Per-entry InChI files | Individual InChI string for each input molecule |
batch.tsv | Combined tab-separated file with all input identifiers and their InChI strings |