Iceland Kennitala validator
How the Kennitala format works
- Format
- 10 digits
- Example
- 0902862349
Things to watch for
- The check digit is a weighted mod-11 sum over the first 8 digits only — the 10th digit is a century marker (0 for the 2000s, 8 or 9 for the 1800s/1900s) and is never part of the checksum
- A computed check value of 10 has never been issued in the kennitala scheme, so those numbers are always rejected even if the format looks right
- The first 6 digits encode a date of birth (DDMMYY) — we validate format and checksum only, never the date, and never store what you enter
^[0-9]{10}$A kennitala is Iceland’s 10-digit national identification number, issued by Þjóðskrá (Registers Iceland) to every resident and used for banking, taxes, healthcare, phone contracts, library cards, and effectively any transaction that requires identifying who you are. It’s built from real information: the first six digits are a date of birth (DDMMYY), the next two are a serial number for that day, the ninth digit is a check digit, and the tenth is a century marker distinguishing someone born in the 1800s, 1900s, or 2000s.
One structural detail sets a kennitala apart: the check digit is calculated purely from a weighted mod-11 sum over the first eight digits, and the century marker that follows it is never part of that calculation — it’s simply appended afterward. A computed check value of 10 is also treated as a hard reject rather than remapped to another digit, because Iceland’s civil registry has never issued a kennitala where that value would occur. Culturally, too, a kennitala is notable for how openly it’s used — given Iceland’s small population, it functions closer to a universal reference number than a guarded secret, appearing on membership cards and routine forms in a way that would be unusual for a comparable identifier in a larger country.
How this validator works
This tool confirms the input is 10 digits, then reruns the weighted mod-11 sum over the first eight digits — ignoring the century marker entirely — and checks the result against the ninth digit, with a computed value of 10 rejected outright. Everything runs in your browser; nothing you enter is transmitted or stored.
What a pass doesn’t tell you
A matching check digit confirms the first nine digits are arithmetically consistent — not that the kennitala was ever issued by Þjóðskrá or belongs to a real person. This tool never decodes or displays the date of birth it encodes.
Scope: this page covers kennitala format and checksum validation only — not identity or registration lookups.
Content last reviewed 2026-08-09.
Kennitala FAQ
What do the 10 digits of a kennitala encode?
The first six digits are a date of birth (DDMMYY), the next two are a serial number issued that day, the ninth digit is a check digit, and the tenth is a century marker — 0 for the 2000s, 8 or 9 for the 1800s and 1900s.
Why is the century marker excluded from the checksum?
The check digit is calculated purely from a weighted mod-11 sum over the first eight digits — the date of birth and daily serial. The century marker is appended afterward and never enters that calculation, so two kennitölur with the same first eight digits but different centuries share the exact same check digit.
Is it true that a kennitala is treated more openly in Iceland than similar numbers elsewhere?
Yes, and it's a genuinely distinguishing fact about the system: a kennitala is used for banking, taxes, phone contracts, gym memberships, and countless everyday transactions, and Icelanders routinely share or look one up the way people elsewhere might share a name — it isn't guarded as closely as, say, a US Social Security number.