IMEI Validator & TAC Breakdown
Is that fifteen-digit number even a real IMEI? Check the Luhn digit, split out the Type Allocation Code, and see the arithmetic — all in your browser, offline.
Nothing is sent anywhere. The check digit maths runs in your browser.
What the fifteen digits are made of
An IMEI is not an arbitrary string. Digits 1 to 8 are the Type Allocation Code, issued to a manufacturer for one specific model variant — which is why a lookup can name your handset before it queries any network. Inside that, digits 1 and 2 are the Reporting Body Identifier, naming the organisation that allocated the code: 01 for the North American body, 35 for the British one, 86 for the Chinese authority, 91 for India, 99 for allocations made directly by the GSMA.
Digits 9 to 14 are the unit serial within that model, with no meaning outside the manufacturer. Digit 15 is the check digit, computed from the other fourteen with the Luhn algorithm — the same checksum that guards payment-card numbers. Its only job is to catch a single mistyped or transposed digit before it reaches a database and returns somebody else's phone.
The check digit, worked through
Take 490154203237518. Drop the final digit and you are left with the fourteen that generate it. Counting from the right of those fourteen, double every second digit; if doubling takes a digit above nine, subtract nine. Add all fourteen resulting values. The check digit is the number that brings that total up to the next multiple of ten — so a total of 72 gives a check digit of 8.
That is the whole mechanism, and it is why the validator can tell you an IMEI is impossible without asking anyone. It is also why "my IMEI is invalid" almost always means a typo rather than a fake phone: swap two digits by accident and the checksum fails immediately.
What a failed check actually means
In order of likelihood: you mistyped it; you copied it from a listing where the seller mistyped it; the number was read badly from a photo; or the number was invented. Re-read it from *#06# on the handset itself before concluding anything sinister — but if a seller's "IMEI" repeatedly fails a checksum that a real one cannot fail, that is information.
A blank, zero or "null" IMEI is a different and more serious signal. Every working handset has one, so a device that reports nothing has had its identity erased or corrupted — usually by a bad firmware flash or a deliberate attempt to hide a blocked phone. Such a handset generally cannot register on a network at all.
Valid? Now check its status — free
See device, blacklist and lock status in seconds — no signup. Dial *#06# on the phone to display its IMEI — or scan a photo or screenshot of that screen, or of the barcode on the phone's box or SIM tray.
100% free · no signup · no card needed
Questions about this tool
How do I know if an IMEI number is valid?
A valid IMEI is exactly 15 digits and its last digit is a Luhn checksum of the first fourteen. Paste the number into the validator above and it recomputes that checksum: if the digit the maths produces is not the digit on the end, the number was mistyped or invented. A valid checksum does not prove the phone exists or is clean — it proves the number is well formed, which is the first thing to rule out.
What does the validator actually check?
Three things, all offline in your browser: the length (15 digits, or 16 for an IMEISV), the Luhn check digit, and the structure — which allocating body issued the code, the eight-digit Type Allocation Code that identifies the model, and the six-digit unit serial. No part of this needs a network connection, and nothing you type is sent anywhere.
Why does a valid IMEI still return "unknown" in a check?
Because validity and history are different questions. The check digit only proves the number is well formed. Whether a database holds a blacklist report or a lock status for it depends on whether that handset was ever reported, and by whom. An IMEI can be perfectly valid and simply have no record anywhere, which is common for phones from markets the big feeds do not cover well.
My IMEI has 16 or 17 digits. Is it wrong?
Probably not. A 16-digit number is usually an IMEISV, where the final check digit is replaced by a two-digit software-version code, and 17-digit strings are often an IMEI with the version appended. Use the first 14 digits plus the correct check digit — or simply dial *#06#, which shows the plain 15-digit form.
Can I work out the check digit myself?
Yes, and the breakdown above shows the arithmetic. Double every second digit counting from the right of the first fourteen, subtract nine from any result above nine, add all fourteen values together, and the check digit is whatever takes that total up to the next multiple of ten. It is the same Luhn algorithm used on payment cards.
Does the validator send my IMEI anywhere?
No. The validation and the breakdown run entirely in your browser — you can disconnect from the network and they still work. Only the optional "run the full check" button sends the number anywhere, and that is the same free lookup the rest of the site uses.