How IMEI Check Digits Work

Updated May 2026

The last digit in an IMEI is a check digit calculated from the earlier digits using the Luhn algorithm.

This check digit does not make a value real or assigned, but it does make the number structurally valid for systems that validate format.

Why a check digit exists

A check digit helps catch simple entry mistakes such as mistyped or transposed digits.

Validation logic in forms and APIs often checks whether the IMEI passes the expected algorithm before accepting it.

A generator starts with a device prefix or TAC-based sequence, computes the final digit, and returns a 15-digit result.

This is useful in QA because it produces sample values that look correct to validation layers.

Passing the Luhn check does not mean the IMEI belongs to a real device, network record, or customer asset.