This article explains what XLSB files are, how they differ from other Excel formats, how to open an XLSB file, and how to convert an XLSB file to various other formats such as PDF, CSV, XLSX, etc.

An XLSB file is a binary Excel workbook file. They store information in binary format rather than XML, as most other Excel files do (e.g. XLSX).

Because XLSB files are binary, they can be read and written much faster, making them extremely useful for very large spreadsheets. When working with large spreadsheets, you may also notice smaller file sizes when using XLSB versus XLSX.

XLSB files store spreadsheet data just like any other Excel workbook format. Workbooks can contain multiple worksheets, and within each worksheet is a collection of cells organized by rows and columns, where text, images, charts, and formulas can exist.