Convert XLB to XLSX

A receiving application may require an .xlsx workbook for editing, sharing, or archiving, but an .xlb file is usually an Excel settings file rather than the spreadsheet itself. The practical solution is to find the original workbook and save that file as .xlsx.

What the XLB format is

.xlb is a proprietary binary file used by desktop versions of Microsoft Excel to store customized toolbars, menus, command bars, and related user-interface settings. Excel usually places files such as Excel.xlb or version-specific names in a user-profile or application-data folder.

An XLB file normally contains no worksheets, cell values, formulas, charts, or workbook structure. It therefore cannot provide spreadsheet content for an XLSX file. The file may appear when restoring an old Excel profile, migrating a Windows installation, or troubleshooting customized Excel commands.

What the XLSX format is

.xlsx is the Office Open XML workbook format used by current desktop and web versions of Microsoft Excel and supported by LibreOffice Calc, Google Sheets, and many spreadsheet-processing libraries. It is a ZIP package containing XML files for worksheets, values, formulas, formatting, charts, tables, and workbook metadata.

XLSX is suitable when a current Excel workbook is required or when spreadsheet data must be exchanged across platforms. It is usually smaller than the older binary .xls format, although the size depends on the workbook contents. XLSX does not preserve VBA projects; a macro-enabled workbook must normally be saved as .xlsm.

How to obtain an XLSX file

There is no meaningful direct conversion from XLB to XLSX. Renaming filename.xlb to filename.xlsx only changes the filename extension and can make the file appear corrupted.

1. Make a backup copy of the XLB file and leave the original unchanged.
2. Search the same folder, the computer, external drives, and cloud-storage folders for the associated workbook. Check for .xls, .xlsx, .xlsm, .ods, and other spreadsheet extensions; use Excel's Recent files list if available.
3. Open the actual workbook in Microsoft Excel and select File → Save As. Choose Excel Workbook (*.xlsx), enter a new filename, and save it. Keep the original workbook until formulas, formatting, charts, and links have been checked.
4. For an older .xls workbook, Excel is usually the safest converter. LibreOffice Calc can open many .xls files; select File → Save As and choose Excel 2007–365 (*.xlsx).

If the XLB came from a non-Microsoft application, open it with that application and use its documented export option. If someone sent the XLB as a supposed spreadsheet, request the original workbook or a valid spreadsheet export.

Online conversion options

Online services cannot reconstruct worksheet data from an XLB file, so submitting one to a converter is not useful. For a real .xls workbook, services such as CloudConvert and Zamzar can convert to .xlsx through a browser; upload only the workbook, download the result promptly, and verify the provider's retention and deletion policy. Do not upload confidential workbooks when local Excel or LibreOffice can perform the conversion.

Compatibility and data loss

Saving a genuine workbook as XLSX can alter unsupported formulas, external links, fonts, print settings, charts, named ranges, or other application-specific features. Review important sheets and formulas after conversion. VBA macros require .xlsm, and Excel toolbar customizations stored in XLB are not transferred to any workbook format; related macros may instead reside in an add-in or macro-enabled workbook.