Aadhaar Masking Tool
Convert a 12-digit Aadhaar number into the UIDAI-recommended masked format that shows only the last four digits, and verify it against the Verhoeff checksum — entirely offline.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
Type the sample number 2345 6789 0124. The tool strips the spaces, confirms it is 12 digits starting with a digit from 2 to 9, and runs the Verhoeff checksum — which this number passes, so the status reads Valid Aadhaar format ✓. The masked version comes out as XXXX XXXX 0124: only the last four digits remain visible, which is the format UIDAI recommends for sharing. (This sample is a synthetic checksum-valid number, not a real Aadhaar.)
How it works
Every Aadhaar number ends in a check digit computed with the Verhoeff algorithm, a checksum designed to catch every single-digit typo and every adjacent-digit swap. The tool strips non-digits from your input, requires exactly 12 digits with a first digit of 2–9 (Aadhaar numbers never begin with 0 or 1), then runs the digits through the Verhoeff dihedral-group tables; a final state of zero means the checksum passes. Valid numbers are then masked by replacing the first eight digits with X, leaving only the last four visible — the exact format UIDAI recommends for everyday sharing.
Good to know
UIDAI itself recommends the masked form of Aadhaar for most everyday purposes. A masked Aadhaar shows only the last four digits of the number (the first eight are hidden), alongside your name, photo and demographic details — enough for most identity checks without exposing the full number. You can download an officially generated masked Aadhaar PDF from the UIDAI website or the mAadhaar app by ticking the masked-Aadhaar option, and DigiLocker also stores an Aadhaar view that avoids exposing the full number in print-outs you hand over.
The Verhoeff checksum this tool runs is the same algorithm UIDAI uses to compute the twelfth digit of every Aadhaar number. It is a purely mathematical self-consistency check: it will catch virtually every typo — a single wrong digit or two swapped neighbouring digits always breaks the checksum. What it cannot do is tell you whether a number was actually issued, is active, or belongs to the person presenting it. A checksum-valid number may simply never have been assigned. Real verification of existence and ownership requires UIDAI's own authentication or QR-code verification services; treat this tool strictly as a format and typo check.
If you are reluctant to share even a masked Aadhaar, UIDAI offers the Virtual ID (VID) — a temporary, revocable 16-digit number mapped to your Aadhaar that you can generate from the UIDAI portal or mAadhaar app and give to agencies instead of the real number. Authentication against a VID works exactly like Aadhaar authentication, but the agency never learns your actual Aadhaar number, and you can regenerate the VID at any time to invalidate the old one.
Hotels, verification desks and most service providers can and should accept a masked copy — MeitY and UIDAI guidance is explicit that the full number rarely needs to be collected, and organisations that store full Aadhaar numbers take on real regulatory and breach risk under the Aadhaar Act and India's data-protection rules. When you must submit a photocopy, write the purpose and date across it. And a note on privacy here: this page performs the masking and checksum entirely in your browser with JavaScript. The number you type is never transmitted, logged or stored — you can load the page, disconnect from the internet, and it still works.
Frequently asked questions
What is a masked Aadhaar and when should I use it?
A masked Aadhaar hides the first eight digits of your 12-digit number, showing only the last four (XXXX XXXX 1234) along with your name and photo. UIDAI recommends it for everyday identity checks — hotels, couriers, verifications — because it proves identity without exposing the full number.
Is the Aadhaar number I type here uploaded anywhere?
No. The masking and Verhoeff checksum run entirely in your browser using JavaScript — nothing is sent to any server, and nothing is logged or stored. You can load this page, switch off your internet connection, and the tool keeps working exactly the same.
Does passing the checksum mean an Aadhaar number is real?
No. The Verhoeff checksum only proves the number is self-consistent — that it could be a validly formed Aadhaar and contains no obvious typo. It does not prove the number was ever issued or belongs to a particular person. Only UIDAI's authentication or QR verification services can confirm that.
Why does my Aadhaar number fail validation here?
Three common reasons: a typo (the Verhoeff checksum catches any single wrong digit or swapped pair), fewer or more than 12 digits entered, or a number starting with 0 or 1, which UIDAI never issues. Re-check each digit against your card; if it still fails, the number as typed is not a validly formed Aadhaar.
People also ask
How do I download a masked Aadhaar card officially?
Go to the UIDAI website (uidai.gov.in) or the mAadhaar app, choose Download Aadhaar, enter your Aadhaar number or VID, and tick the 'masked Aadhaar' option before requesting the OTP. The PDF you receive shows only the last four digits of your number and is valid for most identity checks.
What is the Verhoeff algorithm used in Aadhaar?
It is a checksum scheme based on the dihedral group D5 that UIDAI uses to compute the 12th digit of every Aadhaar number from the first 11. It detects all single-digit errors and all adjacent transpositions, so nearly any typo in an Aadhaar number makes the checksum fail.
Is it safe to share a masked Aadhaar copy with a hotel?
It is far safer than sharing the full number — that is exactly why UIDAI recommends the masked format. The hotel can verify your name and photo while the first eight digits stay hidden. If you want even more protection, generate a Virtual ID (VID) from UIDAI and share that instead.
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