What Is a CAS Number?

Supplier feeds for adhesives, lubricants, coatings, and cleaning agents rarely name the same substance the same way twice. One vendor writes “Isopropyl Alcohol,” another writes “IPA,” a third lists the IUPAC name “propan-2-ol,” and a fourth omits any chemical name altogether. When your PIM or ERP needs to trigger a hazard warning, route a shipment correctly, or run a restricted-substance check, free-text chemistry fields fail completely. A validated CAS number is the single join key that resolves all of those variants to one canonical substance — and Claro’s enrichment platform automates the work of locating, validating, and writing that key back into every affected record before the data reaches your downstream systems.

Definition

A CAS Registry Number (written CAS RN or CAS No.) is a unique numeric identifier assigned by the Chemical Abstracts Service to a specific chemical substance. The format is XXXXXXX-YY-Z: the first group can be two to seven digits, the second group is always two digits, and the final single digit is a check digit calculated from the others. The number itself carries no chemical meaning — it is a stable pointer that maps one entry in the CAS registry regardless of what trade name, synonym, or language a supplier uses.

Water is 7732-18-5. Titanium dioxide is 13463-67-7. Isopropyl alcohol is 67-63-0. The same substance gets the same number every time, which is exactly why safety data sheets, regulatory candidate lists, and ingredient declarations cite the CAS number alongside the chemical name rather than relying on the name alone.

Why CAS numbers matter for product data

The core value is disambiguation at scale. A single substance can appear in supplier feeds under dozens of names — systematic IUPAC names, common names, brand names, abbreviations, and misspellings in several languages. A validated CAS number collapses all of those variants to one canonical identifier, making it the most reliable join key available for chemical content in a catalog.

Three cross-industry scenarios illustrate the pattern:

• MRO distribution: A distributor receiving adhesives, lubricants, and cleaning chemicals from fifty vendors uses CAS numbers on incoming safety data sheets to link each product to the correct hazard, storage, and shipping rules — even when each vendor names the same solvent differently.
• CPG and personal care: A formulator reconciles an ingredient declared as Aqua on one line with water on another. Without a CAS number, those records match only on human judgment; with one, the join is deterministic.
• Furniture and materials compliance: An importer screening finishes and foams against restricted-substance lists matches supplier material data by CAS number rather than by marketing description, which would otherwise slip past a keyword filter when trade names vary.

Once a record is keyed to a verified CAS number, you can attach SVHC status, RoHS relevance, Prop 65 warnings, and transport classifications without re-keying chemistry by hand. Claro resolves incoming substance names to validated CAS numbers, flags records where no CAS number exists or where the check digit fails, enriches those gaps from authoritative sources, and writes clean values back into your PIM or ERP — so the compliance layer downstream operates on trusted identifiers, not guesses.

Before and after: messy vs. trusted chemical data

CAS numbers versus other product identifiers

A CAS number sits at the substance level — below the level of a sellable product. Understanding where it fits relative to other identifiers prevents catalog design mistakes.

One finished SKU can contain several substances, each with its own CAS number. That is precisely why a clean chemical key is so valuable when you reconcile messy multi-supplier data: the product-level identifiers (GTIN, MPN) tell you what you are selling, and the CAS numbers tell you what it is made of.

Related

FAQ

How many digits is a CAS number? +

A CAS number has up to ten digits arranged in three hyphenated groups, formatted as XXXXXXX-YY-Z. The first group ranges from two to seven digits, the middle group is always two digits, and the last is a single check digit. Shorter substances such as water (7732-18-5) simply use fewer digits in the first group.

How is the CAS check digit calculated? +

The final digit is a checksum. Reading the digits to its left from right to left, each is multiplied by its position (1, 2, 3, and so on), the products are summed, and the remainder after dividing by 10 is the check digit. This lets a validator catch transposed or mistyped numbers before they enter your catalog.

Is a CAS number the same as a product or SKU number? +

No. A CAS number identifies a chemical substance, not a sellable product. A single SKU can contain several substances, each with its own CAS number, while product-level identifiers such as GTIN or MPN identify the packaged item you actually sell. They operate at different levels and are often used together.

Where do I find the CAS number for a product? +

The most reliable source is the supplier safety data sheet (SDS), which lists CAS numbers for the relevant substances, usually in Section 3. Ingredient declarations, technical data sheets, and regulatory filings also cite them. When a feed gives only a chemical name, validate any CAS number you derive before trusting it.

Why do CAS numbers matter for compliance screening? +

Restricted-substance lists such as the EU SVHC candidate list and California Prop 65 are published by CAS number, not by trade name. Keying your records to validated CAS numbers lets you screen against those lists automatically and consistently, instead of relying on keyword matching against free-text descriptions that may miss synonyms or misspellings.