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IMEI Validator (US Carriers)

Everyday

Validate an IMEI number and detect the US carrier network (AT&T, Verizon, T-Mobile) from the TAC prefix. Checks Luhn checksum. Free, client-side.

Reviewed by the thecalcu.com team · Last updated July 17, 2026

What is a IMEI US?

An IMEI validator for US carriers checks whether a 15-digit IMEI (International Mobile Equipment Identity) number is structurally valid using the Luhn algorithm, and provides additional context about the device type based on the TAC (Type Allocation Code) prefix. The IMEI is the unique identifier of every mobile phone handset and is used by US carriers, AT&T, Verizon, T-Mobile, and MVNOs, to identify devices on their networks.

Every mobile phone manufactured for sale in the US must have an IMEI assigned under the GSMA's IMEI allocation framework. The number is encoded in the device's firmware and cannot be legitimately changed. When a device is reported stolen, carriers add its IMEI to a shared blacklist (the GSMA CEIR), preventing it from being activated on any participating network. When purchasing a used phone, checking the IMEI is a standard due-diligence step.

The Luhn checksum, the 15th digit of the IMEI, is a mathematical check digit that makes single-digit transcription errors detectable without a database lookup. If you dial *#06# and receive a 15-digit number, the last digit is the Luhn check. This validator confirms that the check digit is mathematically consistent with the preceding 14 digits, confirming the number is at least structurally plausible.

This validator goes beyond the basic Luhn check by parsing the 8-digit TAC and providing a device hint for well-known manufacturer TAC prefixes, giving you a quick indicator of the device's origin. Use it alongside the FCC ID Validator for full device compliance checking.

Why Use an IMEI Validator?

The most common use case is verifying a used phone before purchase. A seller claims the phone is a genuine iPhone 15, dial *#06# and read the IMEI, then validate it here. A failed Luhn check means the number is incorrect or the device may have a tampered IMEI, which is a strong warning sign.

For developers building carrier integration platforms, the format check is a standard first step before submitting an IMEI to a carrier's activation or unlock API.

Who Should Use This Validator?

Consumers buying used phones from online marketplaces or private sellers can quickly confirm the IMEI is structurally valid before parting with money. A Luhn failure is immediate grounds for suspicion.

Mobile phone retailers accepting trade-ins can use the validator as a quick format check before submitting the IMEI to carrier unlock or buyback systems.

Developers building mobile device management (MDM) platforms, carrier portals, or device finance applications need IMEI validation as a front-end check before backend carrier API calls.

Corporate IT teams managing device inventories for BYOD (Bring Your Own Device) programmes can validate employee-submitted IMEIs before adding them to the MDM system.

What Insights Does the IMEI Validator Give You?

A valid result shows the three parts of the IMEI: the 8-digit TAC, the 6-digit serial number, and the check digit. It confirms the Luhn checksum passed. Where a TAC prefix is recognised, a device type hint is shown, this is indicative only.

An invalid result identifies the specific problem: incorrect length, non-numeric characters, or a Luhn checksum failure. A Luhn failure on an otherwise plausible 15-digit number suggests the number was transcribed incorrectly.

How to use this IMEI US calculator

  1. Dial *#06# on the device to display the IMEI, or find it in Settings > About Phone.
  2. Enter or paste the 15-digit number into the IMEI Number field. Hyphens and spaces are stripped automatically.
  3. The result shows immediately: Valid with parsed TAC, serial, and check digit, or Invalid with the specific issue.
  4. If valid, proceed to a carrier IMEI check to confirm the device is not blacklisted or finance-locked.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Luhn algorithm (same as credit card validation):

Starting from the rightmost digit (position 1, the check digit), alternate doubling every second digit:
- Odd positions (1, 3, 5, ...): add the digit as-is
- Even positions (2, 4, 6, ...): double the digit; if the result > 9, subtract 9

Sum all values. The IMEI is valid if sum % 10 === 0.

Example:
IMEI: 352093111951945

| Pos | Digit | Double? | Value |
|---|---|---|---|
| 1 | 5 | No | 5 |
| 2 | 4 | Yes (4×2=8) | 8 |
| 3 | 9 | No | 9 |
| 4 | 1 | Yes (1×2=2) | 2 |
| ... | ... | ... | ... |

Sum = 30, 30 % 10 = 0 → Valid

IMEI structure:
- Digits 1–8: TAC (Type Allocation Code), manufacturer and model
- Digits 9–14: Serial number, unique per device
- Digit 15: Check digit (Luhn)

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Frequently Asked Questions

What is an IMEI number?
An IMEI (International Mobile Equipment Identity) number is a unique 15-digit identifier assigned to every mobile device. It is used by carriers and regulators to identify individual handsets on cellular networks, block stolen devices, and track device eligibility for network activation. No two devices should share the same IMEI.
What does the IMEI US validator check?
The validator checks that the 15-digit IMEI passes the Luhn checksum algorithm, which is the standard mathematical validity test for IMEIs. It also parses the TAC (Type Allocation Code, the first 8 digits) and provides a device hint for some known TAC prefixes. It does not contact any carrier database.
What is the Luhn algorithm and why does IMEI use it?
The Luhn algorithm is a simple checksum formula used to detect single-digit transcription errors. It works by doubling every second digit from the right, summing all digits, and checking that the total is divisible by 10. IMEIs (and credit card numbers) use Luhn so that a single mistyped digit is reliably detected without a database lookup.
What is a TAC code in an IMEI?
The TAC (Type Allocation Code) is the first 8 digits of the IMEI. The first two digits of the TAC indicate the reporting body that authorised the device (e.g. BABT in the UK, PTCRB in the US). The remaining 6 TAC digits identify the specific device model. Together the TAC uniquely identifies the make and model of the device.
Does a valid IMEI mean my device is not blocked or blacklisted?
No. The Luhn check confirms the 15 digits are mathematically valid, it cannot tell you whether the device is active, stolen, blacklisted, or financed. Checking a device's blacklist status requires a query to the US carrier's IMEI database (GSMA CEIR) or a third-party IMEI lookup service.
Where do I find my device's IMEI?
Dial *#06# on any mobile device to display the IMEI on screen. Alternatively, it is printed on the box the phone came in, on the SIM tray of most iPhones, and in Settings > About Phone (Android) or Settings > General > About (iPhone). On older phones, it may be on the battery compartment label.
What is the difference between IMEI and MEID?
IMEI is the 15-digit identifier used by GSM/LTE devices (AT&T, T-Mobile) and most modern smartphones. MEID (Mobile Equipment Identifier) is a 14-digit identifier used by older CDMA devices (originally Verizon and Sprint). Most modern US devices use IMEI, as the major carriers have migrated from CDMA to LTE/5G.
Can I check if a used phone is clear to activate on a US carrier?
This validator confirms only the Luhn checksum format. To check carrier compatibility and activation status, use the specific carrier's IMEI check tool (AT&T, Verizon, and T-Mobile all offer free IMEI checks on their websites). This formatter is useful as a first-pass format check before submitting to a carrier API.
Is my IMEI data stored or uploaded anywhere?
No. The validation runs entirely in your browser. Your IMEI is never sent to a server or stored. This is important, the IMEI is device-specific and can be used to track device history, so you should share it only with trusted parties.
What makes a US-specific IMEI validator different from a generic IMEI validator?
A US IMEI validator includes TAC-to-carrier hinting for common device prefixes sold in the US market. This provides an indicative (not definitive) note about whether the device TAC is associated with a particular US carrier network. The underlying Luhn check is the same globally.
Can two different phones have the same IMEI?
Legitimate devices should never share an IMEI, each is factory-assigned and unique. Cloned or counterfeit devices sometimes copy the IMEI of a legitimate device, which causes network conflicts and carrier issues. If a carrier reports that your IMEI is already in use on another active device, the phone may be cloned.
Also known as
IMEI US carrier checkAT&T IMEI checkVerizon IMEIT-Mobile IMEIUS IMEI validator