# Filter by molecular weight

When searching chemical structures in SureChEMBL, you may specify a particular range of molecular weights that are considered acceptable results. The default range of zero to 800 is designed to encompass the majority of small molecules most of interest to medicinal chemists.

<figure><img src="/files/gN0oPOn9IiYjh8jho7GC" alt=""><figcaption><p>Molecular weight filter</p></figcaption></figure>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://chembl.gitbook.io/surechembl/chemical-search/filter-by-molecular-weight.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.