What is the MIG file format?
.mig files are used by migration utilities built into Microsoft Windows and by enterprise deployment tools from the Windows Assessment and Deployment Kit (ADK). They store Windows user account data, including:
- program settings,
- system configuration,
- user accounts,
- associated resources (files, folders, archives),
- system registry keys.
Files with the .mig extension are created by two Microsoft programs: Windows Easy Transfer and the Microsoft User State Migration Tool (USMT). Both tools are used for migrating accounts and personal settings across Windows systems. USMT is the tool of choice for larger-scale, multi-system migrations; its migration store is typically named USMT.MIG. In contrast, Windows Easy Transfer is typically used for migrating accounts between individual Windows machines. .mig files can also be used when updating Windows systems.
Introduced with Windows Vista in 2007, Windows Easy Transfer was removed in Windows 10. Users on Windows 10 or Windows 11 must use USMT (from the Windows ADK) or a third-party tool such as PCmover to read existing .mig stores. The format is a proprietary compressed binary container - distinct from generic archive formats such as .WIM - and supports optional password-based (AES) encryption. The internal format version is tied to the Windows or USMT version that created it, so cross-version restores can sometimes fail.
.mig files are stored on the target machine for the account migration. They can also be placed on a remote host or the source machine. Microsoft's migration tools allow users to store .mig files on external storage devices such as USB drives, on network shares, or on CD/DVD discs. Due to the volume of data captured, files typically range from hundreds of megabytes to several gigabytes.
Security & safety
RISK: LOWA .mig migration store is data, not an executable, so the file itself won't run code. The real concerns are restore-related: it can be password-protected (lose the password and the data is unrecoverable), it may be large, and restoring it overwrites or merges profile settings on the destination PC. As privacy, it can contain an entire user profile (documents, saved credentials in settings), so store it securely and avoid uploading it to untrusted online "MIG opener" sites - there is no real web tool for this format and such pages are typically scams.
Format details
in a nutshellPrograms that open MIG files
Windows3 apps
Windows Easy Transfer
Built-in On a Windows Vista/7/8.1 PC, run Windows Easy Transfer, choose 'This is my new computer' > 'an Easy Transfer file', select the .mig and enter the password. (Removed from Windows 10/11.)
USMT (loadstate) - Windows ADK
Free Install the Windows ADK, then run 'loadstate.exe <store> ...' to apply a USMT.MIG store. The technical route that works on Windows 10/11.
PCmover (Laplink)
Paid Microsoft's recommended third-party migration tool after Easy Transfer's removal; transfers profiles to new PCs (uses its own format, but is the modern alternative). Technical details
deep spec| Format type | Proprietary compressed binary container (migration store) |
| Encoding | Binary, little-endian byte order |
| Compression | Built-in Microsoft migration-store compression |
| Encryption | Optional password-based (AES) protection, set at creation time |
| Typical file size | Hundreds of MB to multiple GB, depending on user profile size |
| Content captured | User files, folders, program settings, system registry keys, user accounts |
| Creating tool (consumer) | Windows Easy Transfer |
| Creating tool (enterprise) | USMT scanstate (part of Windows ADK) |
| Restore tool (Vista-8.1) | Windows Easy Transfer or USMT loadstate |
| Restore on Windows 10/11 | Requires USMT from Windows ADK or a third-party tool; Windows Easy Transfer not available |
| Supported OS (built-in) | Windows Vista, Windows 7, Windows 8/8.1 |
| Enterprise store filename | USMT.MIG (default name when created by USMT scanstate) |
| Format version compatibility | Internal version tied to Windows/USMT that created it; cross-version restores can fail |
| File signature (magic bytes) | No documented public signature; cannot be identified by generic tools |
| MIME type | application/octet-stream |
| Integrity checking | Internal store integrity verified on restore; corrupt store or wrong password aborts the operation |
| Released | Windows Vista (2007), as the Windows Easy Transfer file format |
| Latest version | Windows 8.1 (last OS to include Windows Easy Transfer; removed in Windows 10) |
| Specification | learn.microsoft.com |
MIG conversions
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