imei check digit calculator

What is an IMEI check digit?

An IMEI (International Mobile Equipment Identity) is a 15-digit number used to identify a mobile device. The first 14 digits carry identification information about the device model and origin, while the 15th digit is a check digit.

The check digit is computed using the Luhn algorithm. Its purpose is simple: catch common typing errors. If someone enters an IMEI with a wrong digit, the check can often detect it immediately.

How this IMEI calculator works

1) For check digit generation

When you enter 14 digits, the tool doubles every second digit (from the left), subtracts 9 when needed, sums everything, and computes the final digit required to make the total a multiple of 10.

2) For IMEI validation

For a full 15-digit IMEI, this page recalculates the expected check digit from the first 14 digits and compares it with the 15th digit you provided.

Why an IMEI validator is useful

• Data quality: Quickly detect mistyped numbers in forms and databases.
• Inventory operations: Verify device identifiers during logistics and warehousing.
• Repair workflows: Reduce errors when registering devices for service.
• Marketplace checks: Validate format consistency before further verification steps.

Step-by-step Luhn method for IMEI

Example with 14 digits: 49015420323751

• Starting from the left, double digits in positions 2, 4, 6, 8, 10, 12, and 14.
• If a doubled value is greater than 9, subtract 9 from it.
• Add all transformed and untouched digits together.
• Check digit = (10 - (sum mod 10)) mod 10.

For this example, the calculated check digit is 8, giving a complete IMEI of 490154203237518.

Common mistakes to avoid

• Using fewer than 14 digits when trying to calculate the check digit.
• Including letters or punctuation in the IMEI input field.
• Confusing a valid check digit with proof that a device is clean or unlocked.

Important note on device status

A valid check digit means the IMEI format is mathematically correct. It does not confirm blacklist status, ownership, warranty eligibility, carrier lock, or theft history. For those checks, use official carrier or manufacturer channels.

FAQ

Is IMEI the same as serial number?

No. The IMEI identifies the radio-enabled mobile equipment format; a serial number is manufacturer-specific and separate.

Can two phones share one IMEI?

Legitimate devices should not share the same IMEI. Duplicate IMEIs may indicate cloning, data errors, or non-compliant hardware.

Does this calculator store my IMEI?

This page performs all calculations in your browser with JavaScript. No server request is needed for check-digit math.