What Is an MDB File?

What is inside

An .mdb file is a Microsoft Access database. It is not a spreadsheet with one grid of cells. A single file can contain:

• Tables. The data itself, in rows and columns, with a declared type per column.
• Relationships. Which table’s key matches which other table’s column.
• Queries. Saved questions asked of the tables.
• Forms and reports. The interface someone built so colleagues could use the database without seeing the tables.

If you need data from an old Access file, the tables are usually the useful part. The forms and reports depend on Access and often on old Windows code.

The file formats

MDB vs ACCDB covers the differences in detail.

Why it will not open on a Mac

Microsoft has never shipped Access for macOS. The database engine that reads these files is also Windows-only. That is why Excel for Windows can import an Access database while Excel for Mac cannot.

The blank icon does not mean the file is damaged. macOS has no app registered to read it.

Getting the data out

Export to CSV if the tables are going into Excel or Numbers. Use SQLite if the database has several related tables or you want to query it with SQL.

How to open an MDB file on a Mac walks through the four ways to do that, including the free ones.