Excel File Extension

Excel Pro Tips

How to Check Excel File Extension (2 Easy Methods)

ExcelInsider Team December 9, 2025

Knowing your Excel file’s extension is important for compatibility, sharing, and choosing the right features. For example, modern Excel uses .xlsx, while older versions use .xls. Other formats, such ...

Excel Pro Tips

[Fixed] Cannot Open the File Because the Extension Is Not Valid

ExcelInsider Team October 11, 2025

Sometimes when you double-click an Excel file, you get the message: "Excel cannot open the file because the extension is not valid." This issue is common among users who receive files from email, ...