Aadhaar Number Validator
Check an Aadhaar number's format and Verhoeff check digit, with a masked view
Runs entirely in your browser. Nothing you type or upload is sent to us or stored. How we handle privacy
Runs entirely in your browser. Nothing you type or upload is sent to us or stored.
Results are for general guidance. Please check anything important before relying on it. Terms of use
How to Use
- Type the 12-digit Aadhaar number. Spaces between the groups of four are fine.
- The result updates as you type: it checks that there are 12 digits, that the number doesn't start with 0 or 1, and that the last digit matches the Verhoeff check digit.
- If the number is complete, you see its masked form (XXXX XXXX and the last four digits). Use Copy masked number when you only need to quote it.
- To find out whether the number is genuine and active, use Verify Aadhaar on UIDAI's myAadhaar portal. This tool only checks the format.
- Press Clear when you're done. The number is never saved or sent anywhere.
What this Aadhaar checker does (and doesn't)
An Aadhaar number is a 12-digit number issued by the Unique Identification Authority of India (UIDAI). Its last digit is a check digit, so most typing mistakes, like one wrong digit or two neighbouring digits swapped, can be caught without contacting anyone. This Aadhaar validator does exactly that, inside your browser.
It only checks the format. A number that passes all three checks is well-formed. That's all. It doesn't tell you the Aadhaar was ever issued, that it's active, or that it belongs to the person who gave it to you, because anyone can make up a number with a correct check digit. To verify a number, use the official Verify Aadhaar service on myAadhaar (uidai.gov.in). It tells you whether the number exists and is active. You can also scan the secure QR code on the Aadhaar letter or e-Aadhaar with UIDAI's QR scanner app.
The three format rules
| Rule | Why |
|---|---|
| Exactly 12 digits | Every Aadhaar number has 12 digits, usually written as three groups of four. |
| Doesn't start with 0 or 1 | UIDAI doesn't issue numbers beginning with 0 or 1. |
| Last digit is the Verhoeff check digit | The 12th digit is worked out from the first 11 with the Verhoeff algorithm. |
How the Verhoeff check works
Jacobus Verhoeff published this algorithm in 1969. It's stronger than a simple "add up the digits" check. It uses three small tables: a multiplication table based on the symmetries of a pentagon, a permutation table that depends on each digit's position, and an inverse table.
for each digit, from the right (position i = 0, 1, 2 …):
c = d[c][p[i mod 8][digit]]
valid if c = 0 at the end
Take a short number as an example. The Verhoeff check digit for 236 is 3, so 2363 passes and 2364 fails. The same method runs over all 12 digits of an Aadhaar number. Verhoeff catches every single wrong digit and every swap of two neighbouring digits. Those are the two most common typing errors, so a failed check almost certainly means a typo.
Masked Aadhaar: share less
A masked Aadhaar shows only the last four digits (XXXX XXXX 1234). UIDAI lets you download one from the myAadhaar portal and advises using it wherever your full number isn't legally required. A few habits worth keeping:
- Give the full number only where it's genuinely required, such as income tax or government benefits.
- Use the masked version or a Virtual ID (VID) when you can. A VID is a temporary 16-digit number you generate on the myAadhaar portal. It stands in for your Aadhaar number during authentication.
- Lock your biometrics on myAadhaar if you don't use fingerprint authentication.
- Never post a photo of your Aadhaar card on social media or send it to unknown numbers.
Your privacy on this page
The check is plain arithmetic done in your browser. The number isn't sent to our server or anyone else. It isn't added to the page address or stored in your browser, and it's gone when you close or clear the page. The result panel only ever shows the masked form.