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IMEI Number Format: Breaking Down the 15 Digits

5 min readUpdated 6/1/2025

Understanding the 15-Digit IMEI Format

An IMEI number always has exactly 15 digits. Each segment encodes specific information about the device. Understanding the format helps you verify that an IMEI is legitimate and what it tells you about the device.

IMEI Structure Breakdown

  • Digits 1–2 (Reporting Body Identifier - RBI) — Identifies the standards body that allocated the TAC (e.g., 35 = BABT/UK, 86 = China, 01 = USA)
  • Digits 3–8 (TAC remainder) — Together with the RBI, forms the 8-digit TAC that identifies the device model
  • Digits 9–14 (Serial Number - SNR) — Unique per device of the same model, assigned by the manufacturer
  • Digit 15 (Check Digit - CD) — Calculated using the Luhn algorithm to validate the entire IMEI string

The Luhn Check Digit

The final digit of every valid IMEI is calculated by the Luhn algorithm — a checksum formula used to validate identification numbers. IMEI Check Pro validates the check digit automatically. An IMEI that fails the Luhn check is either mistyped or fabricated.

IMEI2 on Dual-SIM Phones

Dual-SIM phones have two IMEI numbers (IMEI1 and IMEI2). Both are displayed when you dial *#06#. Either can be used for an IMEI check — both will return the same device model. The premium check queries databases using IMEI1 by default.

IMEISV: The Extended Format

IMEISV (IMEI Software Version) is a 16-digit extension of the IMEI that adds a 2-digit Software Version Number. This is used internally by carriers for network management but is not used for blacklist or spec checks.