Does the SSN have a check digit?

No. Unlike many national ID numbers, the US Social Security Number has no mathematical check digit. Validity is determined purely by structural rules — the area must be 001–899 and not 666, the group must be 01–99, the serial must be 0001–9999, and the number must not be a reserved or publicly advertised number.

Does a valid format mean the SSN was really issued?

No. Because there is no checksum, this tool can only confirm that a number follows the SSA's published format and exclusion rules. It cannot confirm a number was actually issued to a person, and it never queries any government system.

Is my SSN sent anywhere?

No. The validator is privacy-first. All checks run locally in your browser with JavaScript — there are no network requests and your SSN never leaves your device.

US SSN Format Validator — Check Social Security Number Structure

US SSN format validator

Check whether a US Social Security Number follows the structure and exclusion rules published by the Social Security Administration. An SSN is written AAA-GG-SSSS — a 3-digit area, a 2-digit group and a 4-digit serial.

The SSN has no check digit, so validation is entirely structural: the area must be 001–899 and never 666, the group must be 01–99, the serial must be 0001–9999, and the number must not be one of the publicly advertised numbers the SSA has permanently reserved (such as 078-05-1120).

Privacy-first: every check runs in your browser. Nothing is uploaded, stored or sent to any server, and this tool does not query any government database.