.xlt File Extension

What kind of file is a .xlt?

An .xlt file is a reusable Microsoft Excel 97-2003 template. It can hold worksheets, formulas, formatting, charts, named ranges, and active content that become the starting point for new workbooks. Microsoft describes XLT as the BIFF8 binary template counterpart to the .xls workbook, and it commonly uses application/vnd.ms-excel.¹²

Most XLT files begin with the eight-byte OLE Compound File Binary signature:

D0 CF 11 E0 A1 B1 1A E1

That header identifies the container, not Excel or a template. Legacy Word, PowerPoint, and other compound documents share it. Reliable identification also checks for a valid Excel Workbook stream and BIFF records.³

How do I open a .xlt on my computer?

• On Windows or macOS, use Microsoft Excel. Open a trusted XLT through Excel's template workflow when you want a new workbook based on it.
• On Linux, LibreOffice Calc can import and export legacy Excel templates under application/vnd.ms-excel.⁴

Keep an untouched copy before converting an important template. Formula behavior, named ranges, charts, print settings, controls, macros, and external links may change in another spreadsheet application.

Poly support for .xlt

Poly stores, syncs, shares, versions, downloads, and finds XLT files by name. Poly does not currently infer the Excel media type from the .xlt suffix alone. A filename-only upload therefore remains searchable by name instead of automatically receiving spreadsheet processing.

When an upload source supplies application/vnd.ms-excel and processing succeeds, Poly can provide a first-sheet thumbnail, a connected spreadsheet preview, readable-cell search, rendered-sheet similarity, and agent reading of processed sheet text and images. Poly does not run macros, refresh external connections, or replace Excel's editing and formula-auditing tools.

History of .xlt

Microsoft used .xlt for the binary template format associated with Excel 97 through Excel 2003. Its BIFF8 structure belongs to the same legacy family as .xls, but the suffix tells Excel to treat the file as a reusable template rather than an ordinary workbook.¹

Office 2007 introduced XML-based .xltx for templates without macros and .xltm for macro-enabled templates. That split makes active-code capability visible in the modern filename, while a legacy XLT can contain macros without a special macro suffix.⁵

Working with .xlt and alternatives

Legacy templates inherit Excel 97-2003 worksheet limits: 65,536 rows by 256 columns. Modern formats allow 1,048,576 rows by 16,384 columns.⁶

Treat an unexpected XLT as active-capable content. Leave macros and external content disabled unless you trust the file and its sources. For migration, preserve the original, save a reviewed .xltx or .xltm copy, then test formulas, links, controls, and new workbooks created from the template.