.XLSB File Extension

Spreadsheet file created by Microsoft Excel, a program used to create and edit spreadsheets; contains a spreadsheet of cells arranged by a grid of rows and columns, as well as charts, macros, and formatting; saved in a binary format.

XLSB files differ from standard Open XML format (.XLSX) spreadsheets since they store the spreadsheet using a binary format (BIFF12). While they are typically larger in size than the compressed XLSX files, they may perform more efficiently within Excel.

NOTE: XLSB files may be opened by Excel 2007 or later, or by earlier versions of Excel with Open XML support.