.XLSB File Extension

An XLSB file is a spreadsheet workbook created by Microsoft Excel, a program used to create and edit spreadsheets. It contains one or more spreadsheets with cells arranged by a grid of rows and columns, as well as charts, macros, and formatting. XLSB files are 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). You will most likely see and use the XLSX file more often because it is compressed to save space and is easier to share with other users. XLSB files are not compressed, making them larger in size than XLSX files. However, XLSB files may perform more efficiently within Excel because they are saved in the larger binary format.

Depending on the operating system you are using, Excel saves XLSB files in the following locations by default :

Windows Vista, 7, & 10:
C:\Users\<user name>\AppData\Local\Microsoft\Excel\XLStart

Windows XP:
C:\Documents and Settings\Application Data\Microsoft\Excel\XLStart

macOS:
~/Library/Containers/com.microsoft.Excel/Data/Library/Application Support/Microsoft/Roaming/Excel/

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