Aadhaar Number Format: How to Spot Typos and Why to Use Masked Aadhaar

Updated October 20, 20262 min read

Forms ask for Aadhaar numbers everywhere, and a single mistyped digit causes rejected applications and failed KYC. A format check catches most typos instantly — without sending the number anywhere.

The structure

  • 12 digits, usually written in groups of four (XXXX XXXX XXXX).
  • It doesn't start with 0 or 1.
  • The last digit is a Verhoeff check digit calculated from the first eleven.

Why Verhoeff

The Verhoeff algorithm detects every single-digit error and every swap of two adjacent digits — the two most common typing mistakes. If you type 1234 as 1243, the check fails.

Checking a number

The Aadhaar validator checks length, the first digit and the Verhoeff digit in your browser. It doesn't store or send the number, and it shows only a masked version (XXXX XXXX 1234) in the result.

What it cannot tell you

A valid format doesn't mean the Aadhaar exists or belongs to a particular person. Verification of identity is done only through UIDAI's official services (such as the "Verify Aadhaar" feature on the UIDAI website, or authentication by registered agencies). This tool never contacts any of them.

Share less: masked Aadhaar

  • UIDAI lets you download a masked Aadhaar that shows only the last four digits. Many private services accept it.
  • For some uses you can generate a Virtual ID (VID) instead of sharing the number.
  • Don't post photos of your Aadhaar card on social media or send them over chat apps.

Also filling in tax details? Check your PAN's format with the PAN validator.

Try the free tool

Aadhaar Number ValidatorIndiaNewAadhaar check digit, offline and masked.PAN Format ValidatorIndiaNewPAN structure and holder type.

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