CAS requirements

CAS Numbers are assigned by CAS, a division of the American Chemical Society. The CAS Registry database is maintained by CAS and contains the authoritative and internationally recognised list of all CAS Numbers and their chemical associations.

Chemicals on AICS (the Inventory) are listed primarily by their CAS RN and CAS name.

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What is a CAS Registry Number?

A CAS number is a unique and specific identifier assigned to 1 chemical substance or specific mixtures of chemicals.

Why do we rely on CAS numbers?

We use CAS numbers and names for chemicals because they are:

  • internationally recognised
  • unique numbers
  • an accurate source of chemical information
  • a means of verifying a chemical identity
  • able to be validated quickly
What does a CAS registry number look like?

A CAS number contains up to 10 digits which are divided by hyphens into 3 parts. From the left, the first part of the number has 2 to 7 digits and the second part has 2 digits. The final part consists of a single digit.

For example, the CAS number for coconut oil is 61788-47-4.

How do I find a chemical's CAS name and number?

The CAS Chemist Consultation Service can find a CAS number and name for a fee. CAS also has a limited free online resource called Common Chemistry

You may also find CAS numbers Safety Data Sheets (SDS) and chemical catalogues.

Some international government agencies also maintain chemical databases such as the European Chemicals Agency (opens in a new window).

How do I get a CAS number assigned?

The CAS Chemist Consultation Service can assign a CAS number and name for a fee.

Last update 3 September 2019