SSN Validator
Check whether a US SSN is structurally valid under SSA issuance rules — privately, in-browser.
Validate US Social Security Number format instantly. Free SSN checker with area, group and serial rules — format only, fully private.
Calculator Inputs
About SSN Check
Check whether a US SSN is structurally valid under SSA issuance rules — privately, in-browser.
Beyond the XXX-XX-XXXX shape, the SSA never issued area 000, 666, or 900-series numbers, group 00, or serial 0000. This validator enforces the shape plus every never-issued rule and decodes the three parts.
Format-valid says nothing about assignment — only SSA records confirm issuance, and they are rightly inaccessible. Never paste real SSNs anywhere lightly, including here (though nothing leaves your browser). Everything runs locally.
Where it is used
Validating form inputs, testing SSN fields with known-good formats, and teaching SSN structure.
How to use the SSN Check
- SSN (XXX-XX-XXXX) — enter the value (e.g. 078-05-1120).
- Calculate — press the Calculate button to see the result instantly above.
Formula
Format + SSA never-issued rules (area 000/666/900+, group 00, serial 0000).
Examples
Example
Frequently Asked Questions
- Why is 078-05-1120 famous?
- A wallet manufacturer printed it as a sample in the 1930s; thousands adopted it as their own, making it the most misused SSN ever.
- Do area numbers encode geography?
- Historically yes (pre-2011 randomization). Modern SSNs randomize the area, so geography inference is obsolete.
- Can this verify a real person’s SSN?
- No — and that is intentional. Format checks catch typos; issuance verification belongs to authorized SSA channels.