What is an NSN?

An NSN (National Stock Number) is a 13-digit standardized identification number used by NATO and the U.S. military to catalog, buy and manage parts across millions of items.

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Why NSNs exist

The NSN system replaces free-text descriptions and multiple part numbers with one universal reference for each item of supply. This reduces mistakes and speeds up procurement and logistics.

NSN structure

An NSN is usually written as:

XXXX-XX-XXX-XXXX

• FSC (4 digits): Federal Supply Class – item family (e.g. 5305 Screws, 5330 Gaskets).
• NCB (2 digits): National Codification Bureau – country that catalogued the item.
• Item number (7 digits): Unique identifier for that specific item of supply.

NSN vs. part number

A part number belongs to a specific manufacturer. The NSN represents the item of supply and can include multiple approved manufacturers and part numbers under the same record.