Free online WK4 to XLS converter

A legacy Lotus 1-2-3 workbook may need conversion when a recipient, business system, or spreadsheet application accepts Excel .xls files but cannot open .wk4. Converting it also preserves an editable copy for older software that does not support modern .xlsx workbooks.

What the WK4 format is

.wk4 is a binary worksheet format associated with Lotus 1-2-3 Release 4 for Windows. Lotus 1-2-3 was used for business calculations, accounting, reporting, and other spreadsheet work before Microsoft Excel became dominant. A WK4 file can contain cell values, formulas, formatting, named ranges, charts, print settings, and multiple worksheet elements. Most WK4 files now occur in legacy archives and older business records.

What the XLS format is

.xls is Microsoft Excel's binary workbook format used primarily by Excel 97–2003 and supported for compatibility by many newer spreadsheet programs. It remains useful when a receiving system specifically requires Excel 97–2003 format or rejects .xlsx. XLS supports editing, printing, formulas, and workbook formatting, but each worksheet is limited to 65,536 rows and 256 columns, and it is less efficient than the XML-based XLSX format.

How to convert the file

Using 101convert

1. Open the WK4-to-XLS converter on 101convert.com.
2. Select the .wk4 file from your computer.
3. Start the conversion and wait for the .xls file to be generated.
4. Download the result and open it in Microsoft Excel, LibreOffice Calc, or another application that supports XLS.

This option runs without installing desktop software and is available free of charge. Do not upload confidential, personal, regulated, or proprietary workbooks unless the service's privacy, processing, and retention terms are acceptable.

Using LibreOffice Calc

1. Install LibreOffice and open Calc.
2. Choose File → Open and select the WK4 file. If it is not listed, set the file selector to show all files; support for older Lotus formats can vary by LibreOffice version.
3. Allow Calc to use its Lotus 1-2-3 import filter, then inspect the imported sheets, formulas, dates, number formats, hidden rows and columns, column widths, charts, and print settings.
4. Choose File → Save As.
5. Select Excel 97–2003 (*.xls) as the file type, enter a new name such as converted.xls, and save the file.
6. If Calc warns that some content may not be preserved, choose Use Excel 97–2003 Format, not the OpenDocument format.

If Calc cannot open the file, try an available Lotus 1-2-3 Release 4 or 5 installation, or an older Microsoft Excel version with Lotus file import support. Open the workbook there, export it to an Excel-compatible format if available, and save the result explicitly as .xls in a compatible spreadsheet application.

Quality and compatibility limits

Import filters can change Lotus-specific formulas, named ranges, external links, macros, charts, fonts, page breaks, print areas, and date or number formatting. Formula text may translate incorrectly even when displayed values appear valid. Compare important totals, inspect formulas, recalculate the workbook, and check cells containing dates, percentages, currency, leading zeroes, and long numeric identifiers.

Review every worksheet rather than only the first tab. A sheet that exceeds 65,536 rows or 256 columns cannot be represented completely in one XLS worksheet; split the data or use XLSX if the receiving system permits it. Keep the original WK4 file, save the converted workbook under a different name, and verify that the XLS opens correctly before distributing or archiving it.