This article explains the benefits of the ACCDB file format and how to convert between Accdb and MDB file formats in Access for Microsoft 365, Access 2019, Access 2016, Access 2013, Access 2010, and Access 2007.

What to Know

  • To convert an MDF file to ACCDB, open the database in Access 2007 or later and select File > Save As > ACCDB format.To save an ACCDB database as MDB, open the database and select File > Save As > MDB.

ACCDB File Format Benefits

Before its 2007 release, the Microsoft Access database file format was MDB. The ACCDB file format was introduced with Access 2007. While later releases continue to support MDB database files for backward compatibility purposes, the ACCDB file format is the recommended choice when working in Access.

The new format supports functionality that isn’t available in Access 2003 and earlier. Specifically, the ACCDB format allows you to:

  • Include attachments in a database: The ACCDB format allows you to store file attachments and other binary large objects (or BLOBs) in database fields. This feature is common to enterprise databases such as Oracle and SQL Server that had been missing from Microsoft Access.
  • Use multivalued fields: While database purists may scoff at the idea of multivalued fields because these defy the principles of normalization, these fields make life easier for developers of simple databases. Multivalued fields allow users to select one or more options for a field value using checkboxes. For example, you could create a single Shirt Sizes field with the values S, M, L, and XL. Users could then select all values that apply from the multivalued field.
  • Have safe integration with SharePoint and Outlook: SharePoint and Outlook both block MDB databases due to security concerns. Improvements in the database security model allow for the security validation of database files, and both SharePoint and Outlook trust this validation.
  • Feel secure with encryption improvements: Users of ACCDB files can leverage the Windows Cryptographic API for database encryption. This capability is vital to avoid identity theft in which an encrypted database can mean the difference between an embarrassing and costly security incident and a non-event.

Compatibility of ACCDB With Older Access Versions

If you don’t need to share files with databases created in Access 2003 and earlier, then there’s no reason to be backward compatible by using an MDB format.

There are also two limitations that you should consider when using ACCDB. ACCDB databases do not support user-level security or replication. If you need either of these features, you can still use the MDB format.

Converting Between ACCDB and MDB File Formats

If you have existing MDB databases created with earlier versions of Access, you can convert them to ACCDB format. Open the database in any post-2003 version of Access, go to the File tab, then select Save As. Choose the ACCDB format.

You can also save an ACCDB database as an MDB formatted file if you need to work with Access versions before 2007. Follow the same procedure, but choose MDB as the Save As file format.

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