Excel Binary File Format (.xlsb) is a collection of records and structures that specific Excel workbook content.
Here’s how Microsoft defines the XLSB format in their documentation:
Compared to XLSX, XLSB files can be read and written faster which makes it ideal when working with large files.
The reason why some people don’t use XLSB is that if the file is in such format, you couldn’t tell if it has a macro or not.
As you may know, macros could be a source of malicious code.
To save your Excel file in XLSB format, simply select it from the options.
Here’s a comparison of the same worksheet with the same data saved in different formats:
That’s 82% size reduction! Nice! 😊