XLT to XLSM Converter

The XLT format is a legacy spreadsheet template file used by Microsoft Excel versions 97 through 2003. It utilizes the proprietary Binary Interchange File Format (BIFF8), storing formatting, formulas, and baseline data in a binary stream rather than the XML structure of modern formats. These templates serve as blueprints for generating new .XLS workbooks with consistent layouts, preventing the overwriting of the original template file upon saving.

Modern versions of Microsoft Excel retain backward compatibility for XLT files, automatically converting them to the newer XLTX or XLTM format upon saving. Third-party applications such as LibreOffice Calc and Kingsoft Spreadsheets can render XLT templates, though complex formatting or legacy macros may require adjustment. Google Sheets supports importing XLT files, converting them to the native Google Sheets format.

The XLSM format is a macro-enabled spreadsheet file created by Microsoft Excel 2007 and later versions, utilizing the Office Open XML (OOXML) standard (ISO/IEC 29500). Unlike the standard XLSX format, XLSM files store embedded macros written in Visual Basic for Applications (VBA), allowing for automation and complex scripting within the workbook. The file structure relies on ZIP compression to contain XML documents for data, styles, and macro binary parts (vbaProject.bin), presenting a security risk that often requires user authorization to execute active content.

XLSM files open natively in Microsoft Excel (2007+) on Windows and macOS, which provides full VBA execution support. For non-Microsoft environments, LibreOffice Calc, OpenOffice Calc, and WPS Office can open these files and view data, though VBA macro execution compatibility varies significantly. Google Sheets can import XLSM data but strips the VBA macros, converting the file to its native format without automation features.