MDB File Viewer MDB vs ACCDB
MDB vs ACCDB
Both are Microsoft Access databases. .mdb is the Jet format Access used through 2003. .accdb is the format Access has used since 2007.
The differences at a glance
| Access versions | .mdb: Access 2003 and earlier. .accdb: Access 2007 onward. |
|---|---|
| Database engine | .mdb: Jet. .accdb: ACE, a later version of the same engine. |
| Size limit | 2 GB for both. |
| Password | .mdb: a database password with weak protection. .accdb: the password encrypts the file, using AES since Access 2010. |
| User-level security | .mdb only, through a workgroup .mdw file. |
| Replication | .mdb only. |
| Newer field types | .accdb only: attachments, multi-value fields, Large Number and others. |
| Compiled version | .mde for .mdb. .accde for .accdb. |
Why Access changed format
Access 2007 needed field types that Jet could not store. An attachment field holds files inside a record. A multi-value field holds several choices in one cell. Neither fits the .mdb layout.
Microsoft took a private copy of Jet, renamed it ACE and built .accdb on it. Two .mdb features did not make the move: user-level security and replication. Files that rely on either have to stay .mdb.
Encryption is the practical difference
An .mdb password keeps casual users out, but it offers little real protection. An .accdb password encrypts the whole file. Without the password, nothing in it can be read.
That changes which tools work. A reader has to support Access encryption before it can even ask for the password. Many free tools and online converters do not, so they fail on an encrypted .accdb with an unhelpful error. Open an ACCDB file on a Mac covers that case.
Converting between the two
Conversion needs Access, which means Windows. Open the .mdb and choose File, Save As, then Access Database (*.accdb). A replicated database has to be un-replicated first. User-level security does not carry over.
Going the other way, Access can save an .accdb in the 2002-2003 .mdb format. It refuses if the database uses any .accdb-only field type.
Reading either on a Mac
Neither format opens on macOS without help. Microsoft has never made Access for the Mac.
MDB File Viewer reads .mdb and .accdb files from Access 97 through Access 2019, plus the compiled .mde and .accde. That includes Access 97 files, which current Windows versions of Access cannot open. Encrypted .accdb files open once you enter the password.
The free For new work in Access, yes. It has been the default since 2007 and is the only format with the newer field types. Keep Yes, for files in the Access 2000 or 2002-2003 format. Access 97 files are the exception. Access 2013 dropped support for them, so they have to be converted in an older version first. No. The two formats are laid out differently inside. Renaming the file only confuses whatever opens it next. Convert it in Access with Save As.mdbtools reads .mdb well and many .accdb files, but no encrypted ones. How to open an MDB file on a Mac compares all the routes.Questions
Is .accdb better than .mdb?
.mdb only when something depends on it, such as user-level security or an old copy of Access.Can current versions of Access open an .mdb file?
Does renaming .mdb to .accdb convert it?