> For the complete documentation index, see [llms.txt](https://chembl.gitbook.io/unichem/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chembl.gitbook.io/unichem/web-application/similarity-search.md).

# Similarity Search

UniChem [Similarity Search](https://www.ebi.ac.uk/unichem/search/similarity) is an InChI-based search function that will let you find entries for structures similar to your query structure. 

* It is a similarity search using 256 bit Morgan fingerprints and radius=2. 
* Fingerprints are created from the Standard InChI using Tanimoto as a metric.
* The search requires either an InChI string or a molecule structure, and a % threshold at which to cut off results. 

It will return all chemical structures below that threshold from UniChem. Clicking on a structure will show hits for that compound within UniChem sources.

<figure><img src="/files/MVY9OBMgZbQ5FwhzDlnK" alt=""><figcaption><p>Compound results</p></figcaption></figure>

<figure><img src="/files/rMPU8FxaINnZNsYtCWJX" alt=""><figcaption><p>UniCHem records for a given compound</p></figcaption></figure>