An Aadhaar validator that keeps the number on your device
This free Aadhaar validator checks whether a 12-digit Aadhaar number is well formed: twelve digits, a first digit from 2 to 9, and a last digit that matches the Verhoeff check digit UIDAI uses to catch typing mistakes. It is meant for people and developers who need to catch a mistyped number before submitting a form — one wrong digit or two swapped digits are always detected.
Because an Aadhaar number is sensitive, the page is built to keep it private: the digits are hidden as you type, nothing is stored, sent, copied or checked in bulk, and the box is emptied when you leave. A pass means only that the number is well formed. It does not mean the number was issued or belongs to anyone; to verify an Aadhaar, use UIDAI’s own Verify Aadhaar service or an authorised e-KYC.
How to use the Aadhaar Number Format Validator
- Type or paste the 12 digits; they are grouped 4-4-4 and hidden as dots.
- Read the verdict: format valid or invalid, with the reason.
- Tick “Show digits” only if you need to compare what you typed.
- Press Clear when you are done — the page also clears itself when you leave.
- Open the worked example to see how the Verhoeff check works step by step.
Aadhaar Number Format Validator features
Verhoeff check digit
Detects every single-digit error and every swap of two adjacent digits — the most common typing mistakes.
Masked by default
Digits appear as dots; the result shows only the last four, as UIDAI’s masked Aadhaar does.
Nothing kept
No storage, no copy button, no bulk lists, no network requests — and copying out of the field is blocked.
Clear reasons
Wrong length, a first digit of 0 or 1, letters, or a 16-digit Virtual ID typed by mistake.
No guessing aid
It never suggests what the “right” last digit would be, so it cannot be used to complete a made-up number.
Aadhaar number format
Source: UIDAI white paper “A UID Numbering Scheme” (May 2010), which chose the Verhoeff scheme because it catches all single errors and adjacent transpositions, and stresses that the algorithm is public so that anyone can detect keying errors. The UIDAI test numbers come from its developer documentation.
| Rule | Detail |
|---|---|
| Length | 12 digits, usually printed as 4-4-4 (e.g. 9999 4105 7058, a UIDAI test number) |
| First digit | 2–9 for residents; 0 was reserved for future longer numbers and 1 for entities |
| Digits 1–11 | A random, non-repeating number with no meaning — no birth date, place or gender |
| Digit 12 | Verhoeff check digit, computed from the other eleven |
Validation is not verification
- A valid format can still be a number that was never issued, or someone else’s.
- To confirm an Aadhaar exists, use UIDAI’s Verify Aadhaar service at myaadhaar.uidai.gov.in; organisations must use authorised authentication or e-KYC.
- The Aadhaar Act, 2016 restricts how others may collect, store and share Aadhaar numbers — share a masked Aadhaar (last four digits) where full digits are not required.
- Before sharing a scan, hide the number with the image redaction tool or the PDF redaction tool.
Aadhaar Number Format Validator FAQ
How do I validate an Aadhaar card number?
Type the 12 digits into this Aadhaar number validator. It checks the length, the first digit and the Verhoeff check digit on your device and tells you whether the format is valid.
Does a valid result mean the Aadhaar is genuine?
No. It only shows that the number is well formed. Only UIDAI’s services can verify that an Aadhaar number exists.
What is the Verhoeff algorithm?
A check-digit scheme published by Jacobus Verhoeff in 1969, based on the symmetries of a pentagon (the dihedral group D5). UIDAI uses it for the last Aadhaar digit.
Is it safe to type my Aadhaar here?
The check runs in your browser and nothing is saved or sent, the digits are masked, and the field clears when you leave. Avoid doing it on a shared computer all the same.
Why does it not tell me the correct last digit?
On purpose: suggesting check digits would help someone complete a made-up number. If yours fails, read the digits again from the card or e-Aadhaar.
Can an Aadhaar number start with 0 or 1?
No. Residents’ numbers start with 2 to 9; 0 and 1 were reserved in UIDAI’s numbering scheme.