NIC Number Decoder - Birth Date, Gender, Old and New Format
Type or paste a Sri Lankan National Identity Card number to see the birth date, day of the week, gender and age it encodes, and the same number in the other format.
Maintained by Hirantha Sandaruwan Lakshan. Rules checked 13 October 2026 against National identity card (Sri Lanka) - Wikipedia and one more source.
About this tool
Paste a whole list to decode them all at once. The work is done in your browser, so no number is sent anywhere.
How it works
A NIC number is not random. The old format is nine digits and a letter, such as 911042754V. The first two digits are the birth year (91 means 1991), the next three are the day of the year, the next three are a serial number, and the last digit is a check digit, followed by V or X. The new format has twelve digits: a four-digit year, three digits for the day, a four-digit serial number and a check digit.
For women, 500 is added to the day number. A day code of 104 is a man born on the 104th day of the year; 604 is a woman born on that day.
The day count has one quirk. February is always counted as having 29 days, so day 60 is 29 February (which exists only in a leap year) and 1 March is day 61 in every year. In a year that is not a leap year, a day code from 61 onward is therefore one more than the real day of the year, and the decoder takes that into account.
To turn an old number into a new one, put 19 in front of the year, and put a 0 after the three day digits. The reverse works only for people born in the 1900s whose serial number starts with a 0. The check digit's rule is not published, so it is shown but not verified: a well-formed result means the number has the right shape and describes a possible birth date, not that a card with that number exists.
Worked examples
An old number
911042754V is a man born on 13 April 1991, a Saturday. The same number in the new layout is 199110402754.
A woman's number
856154321V: 615 minus 500 is day 115, which in 1985 (not a leap year) is 24 April 1985. The decoder shows her as female.
A list from a spreadsheet
Paste a column of numbers. You get a table with the birth date, weekday, gender and age of each, which you can copy as CSV, and any malformed number is flagged with the reason.
The two NIC layouts
| Part | Old (9 digits + letter) | New (12 digits) |
|---|---|---|
| Birth year | 2 digits (19xx) | 4 digits |
| Day of the year (+500 for women) | 3 digits | 3 digits |
| Serial number | 3 digits | 4 digits |
| Check digit | 1 digit | 1 digit |
| Ending | V or X | none |
Frequently asked questions
Is my NIC number sent anywhere?
No. The number is decoded in your browser as you type and is not sent to this site or anyone else. Even so, treat a NIC as personal information and do not post it publicly.
Does a valid result mean the NIC is real?
No. It means the number is well formed and describes a possible birth date. The check digit's rule is not published, so it cannot be verified, and only the Department for Registration of Persons can confirm that a card exists.
Why does a woman's number have 500 added?
It is how the format records gender: the day of the year is stored as 1 to 366 for men and 501 to 866 for women. A day code above 500 means female.
Why is the date one day off from what I calculated?
February is always counted as having 29 days in the NIC day numbering. In a year that is not a leap year, every date from 1 March is one number higher than a plain day count. Counting 104 days from 1 January 1991 gives 14 April, but the NIC means 13 April.
What do V and X at the end mean?
They only appear in the old format. V is the usual ending; X is also seen. They are commonly explained as relating to voting eligibility, but there is no official specification to cite, so the decoder does not interpret them.
Can I convert a new NIC back to the old one?
Only when the person was born in the 1900s and the first digit of the four-digit serial is 0. Otherwise there is no old-format equivalent.
Sources & references
Updated Oct 13, 2026