IMEI Checksum Validator
Check whether an IMEI is internally valid before you trust a listing.
What you provide
How this calculation works
An IMEI is fourteen digits of identity followed by a check digit calculated with the Luhn algorithm, the same scheme used on payment cards. Doubling every second digit from the right, subtracting nine from anything over nine, and summing the lot must produce a multiple of ten. The check exists to catch a mistyped or transposed digit, and that is genuinely all it does. Enter fourteen digits and the missing check digit is calculated for you instead.
What the results mean
- Check digit
- Valid means the number is internally consistent, so it was almost certainly read and typed correctly. Invalid means at least one digit is wrong.
- Type Allocation Code
- The first eight digits, identifying the model. Turning it into a device name needs the GSMA database, which is not public.
- Serial
- The manufacturer assignment within that model. It carries no information you can decode without the maker records.
Common problems and fixes
- The IMEI on the listing is valid but the phone is blocked
- The check digit and the blocklist are completely unrelated. A stolen phone has a perfectly valid IMEI, which is exactly why it can be blocked by it. Before buying, put the number through your national blocklist service where one exists, and ask the seller to show the number on the device itself using the dialler code rather than on a box.
- The number on the box does not match the number in the settings
- Trust the device. A mismatch means the phone is not the one that shipped in that box, which can be innocent after a warranty replacement and can also mean a board swap or a stolen handset. Either way it needs an explanation before money changes hands, and the number in the settings screen is the one that identifies the device on a network.
Frequently asked questions
Can I find out what phone an IMEI belongs to?
Not from the number alone. The first eight digits identify the model through the GSMA type allocation database, which is not publicly searchable. Sites offering free model lookups are working from scraped and partial copies, which is why they disagree with each other and are frequently wrong on newer devices.
What is the difference between IMEI and IMEISV?
An IMEISV is sixteen digits: the same fourteen-digit identity followed by a two-digit software version instead of a check digit. It appears in network traces rather than on labels, and it has no check digit to validate.
Is it safe to share an IMEI?
Treat it as identifying rather than secret. It cannot be used to access your accounts or your data, but it does identify your specific handset, and sharing it publicly alongside a sale listing has been used to make fraudulent blocklist reports. Show it to a buyer in person rather than posting it.
Put this on your own site
Free to embed, no attribution required beyond the source link the frame carries itself. It runs entirely in your visitor's browser, sets no cookies and loads no third-party script.
<iframe src="https://runthetests.com/embed/imei-validator/" width="100%" height="560" style="border:1px solid #e5e5e5;border-radius:8px" title="IMEI Checksum Validator" loading="lazy"></iframe>
Preview it at https://runthetests.com/embed/imei-validator/. Embedded pages are marked noindex, so yours stays the canonical copy — not this one.