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Aadhaar Number Formatter

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Format raw Aadhaar numbers into the standard XXXX XXXX XXXX spacing, with an option to mask the first 8 digits per UIDAI guidelines. Runs in your browser.

Reviewed by the thecalcu.com team · Last updated 15 July 2026

🇮🇳This tool is specific to India

What is a Aadhaar?

An Aadhaar Number Formatter takes a raw, unformatted 12-digit Aadhaar number and applies the standard display convention, grouped into three sets of four digits, separated by spaces or hyphens. Aadhaar numbers are frequently entered or stored as a continuous 12-digit string in spreadsheets, forms, or databases, but most documents and display contexts expect the conventional grouped format for readability.

This formatter also supports generating a "masked Aadhaar", showing only the last 4 digits, as recommended by UIDAI for situations where the number needs to be displayed but full visibility isn't necessary. It's a formatting tool only, for checking whether a number is structurally valid, use the Aadhaar Validator.

Why Use an Aadhaar Number Formatter?

Aadhaar numbers stored in spreadsheets or database exports are often saved as a single unbroken string of 12 digits, which is harder to read and proofread than the conventional spaced format most people are used to seeing on physical Aadhaar cards. Manually inserting spaces at the right positions across many records is tedious and easy to get wrong.

This formatter handles that instantly, including for bulk lists where you need to reformat many numbers at once. It's also useful whenever an Aadhaar number needs to be shared or displayed but full visibility is a privacy concern, the masking option produces the UIDAI-recommended masked format in one click rather than manually redacting digits.

Who Should Use This Formatter?

  • HR and compliance teams reformatting Aadhaar numbers exported from a database into the standard display format for documents.
  • Developers building KYC or onboarding forms who need to display Aadhaar numbers consistently in the expected grouped format.
  • Customer support and verification staff who need to share a masked Aadhaar number without exposing the full number.
  • Anyone cleaning up a spreadsheet of Aadhaar numbers that were entered inconsistently, some with spaces, some without.
  • Privacy-conscious individuals who want to display a partial Aadhaar number on a form or document without revealing it in full.

What Insights Does the Aadhaar Number Formatter Give You?

The formatter shows you the same Aadhaar number presented in whichever convention you need:

  • Spaced format (XXXX XXXX XXXX), the standard display convention seen on physical Aadhaar cards and most official documents.
  • Hyphenated format (XXXX-XXXX-XXXX), an alternative separator sometimes required by specific forms or systems.
  • Unformatted (XXXXXXXXXXXX), the raw 12-digit string, useful for data entry into systems that don't want separators.
  • Masked output, the UIDAI-recommended privacy-preserving format showing only the last 4 digits.

Processing multiple lines at once also surfaces any input errors immediately, flagging any line that doesn't contain exactly 12 digits so you can fix it before using the data further.

How to use this Aadhaar calculator

  1. Paste one or more Aadhaar numbers into the Raw Aadhaar Input field, one per line.
  2. Select your preferred Output Format, spaced, hyphenated, or unformatted.
  3. Toggle Mask first 8 digits on if you need the privacy-preserving masked version.
  4. Read the formatted result for each line in the output panel.
  5. Check for any "Error" lines, which indicate an input that didn't have exactly 12 digits, and correct the source data.
Show formula & methodology ↓Show less ↑

Formula & Methodology

The formatter strips all non-digit characters from each line, confirms the result is exactly 12 digits, then re-inserts separators at fixed positions.

Before: 234123412346

After (spaced): 2341 2341 2346

After (masked, spaced): XXXX XXXX 2346

No digits are altered, only the separators and, optionally, the visibility of the first 8 digits change.

For background on the underlying term, see our glossary entry on Aadhaar.

Frequently Asked Questions

What is the standard format for an Aadhaar number?
An Aadhaar number is a 12-digit unique identification number issued by UIDAI, conventionally displayed in three groups of four digits separated by spaces, for example, 2341 2341 2346. This formatter applies that standard spacing automatically to a raw, unformatted 12-digit number.
What is a 'masked Aadhaar' and why would I need one?
A masked Aadhaar hides the first 8 digits, showing only the last 4 digits (displayed as XXXX XXXX 1234), which UIDAI recommends for situations where an Aadhaar number must be shared or displayed but full visibility isn't necessary. This formatter includes a toggle to generate this masked version automatically.
Does this formatter validate whether an Aadhaar number is real?
This is a formatting tool, not a validator. It only adds spacing or hyphens to a 12-digit number you provide; it does not check the Verhoeff checksum that real Aadhaar numbers use. Use the [Aadhaar Validator](/aadhaar-validator/) if you need to check whether a number is structurally valid.
Can I format multiple Aadhaar numbers at once?
Yes, enter one number per line in the input box, and the formatter processes each line independently, showing the formatted result (or an error if a line doesn't have exactly 12 digits) on its own corresponding output line.
What happens if I paste a number with spaces or dashes already in it?
The formatter strips all non-digit characters before reformatting, so a number entered as '2341-2341-2346' or '2341 2341 2346' is normalised the same way as a continuous 12-digit string. This means you can paste Aadhaar numbers from almost any source format.
Why would I need the hyphenated or unformatted output options?
Different forms, documents, or systems expect different conventions, some require the standard spaced format, others expect hyphens, and data import systems often need the digits with no separators at all. This formatter supports all three so you can match whatever the destination requires.
Is my Aadhaar number stored or uploaded anywhere?
No, given how sensitive Aadhaar numbers are, this is especially important: all formatting happens entirely in your browser using JavaScript. Nothing you type is sent to a server, logged, or stored anywhere.
Why does masking only affect the first 8 digits and not the last 4?
UIDAI's masked Aadhaar standard specifically preserves the last 4 digits as a partial identifier for verification purposes while hiding the rest, which is why this formatter masks the first two groups and leaves the final group of 4 digits visible.
What should I do if my Aadhaar number formats with an error?
An error means the line you entered didn't have exactly 12 digits after non-digit characters were stripped out. Double-check the original number for a missing or extra digit and re-enter it.
Also known as
format Aadhaar numberAadhaar XXXX XXXX XXXXmask Aadhaar numbermasked Aadhaar generatorAadhaar number spacing