Without doubt 99% of all Excel files are saved in the XLSX format today. However you still have some other file formats available: For instance XLSM, XLSB, or even “older” Excel users can still use the XLS file type. What are the main differences of such file formats? And even more significant: Which one should you use?
If you save an Excel file for the very first time or use the “Save As” command, you will be asked for a folder, file name along with the file type. By default, the system suggests the XLSX file format. So which file extension will you use? The answer – depends on your needs. Before we make a decision, we take a look at the most significant file formats in Excel with their pros and cons first.
The “default” format in excel is XLSX. The massive users of Excel use this file type today. Quite often you save the file in the XLSX format: It’s save (unable to save malicious code) , and offer the maximum quantity of rows and columns and it is really popular . XLSX was launched at Excel 2007 and takes the place of the old XLS extension. It works with the open XML standard which has been saved well.
If you have VBA macros in the XLSX file, you may be required to transform the file format to XLSM. Only this way you can actually save your VBA macros within the Excel file (there exists other file format, e .g . XLSB – but you will not be able to use XLSX for VBA macros). That is why, it has the pros, and cons of the XLSX file format. You can instantly recognize Excel files with VBA macros .This file extension is also not safe and is at risk of viruses. It might include a malicious code due to the VBA macros. It is also incompatible with Excel 2003 .The file format also require a lot of storage space. To learn more about XLSX and XLSM format I highly recommend https://www.am18.co.uk/excel-file-types-xlsm-vs-xlsx/
Many people don’t know that they can use an alternative to the XLSX or XLSM format: The XLSB extension. XLSB workbook store the data a bit different when compared with the XLSX or XLSM extension: They don’t work with the XLM file structure. As an alternative, XLSB files attempt to save storage space as the data files is stored in the binary structure. The big difference: Binary file is computer- but is not human-readable.
XLAM is the format for Excel add-ins. They might contain VBA macros, worksheets along with images, ribbon, and forms. When you double click on this file, it will certainly open in Excel giving you the ability to use the functionality of the add-in. However next time you open in Excel again, it will not be available any more. You have a preference to use the add-in within the options (File –> Options –> Add-Ins).