Free online WK1 to XLS converter

Legacy Lotus 1-2-3 files may need conversion when a current spreadsheet program, accounting system, or archive accepts Microsoft Excel’s .xls format but not .wk1. The conversion preserves usable tables and formulas in a format that is easier to edit and exchange.

What the WK1 format is

.wk1 is the worksheet file format used by Lotus 1-2-3 Release 2.x and related DOS-era versions. It stores cell values, labels, formulas, and selected worksheet formatting. WK1 files commonly remain in legacy accounting, inventory, engineering, and business archives.

Lotus 1-2-3 is discontinued, and support for its file formats varies among current spreadsheet applications. Some versions of LibreOffice Calc and other compatible programs can import WK1 files, but a file may not open correctly if it uses Lotus-specific features or is damaged.

What the XLS format is

.xls is Microsoft Excel’s binary workbook format used primarily by Excel 97–2003 and by applications that support that compatibility format. It can contain worksheets, formulas, cell formatting, charts, named ranges, and other standard spreadsheet data.

XLS is suitable when an older business application specifically requires Excel 97–2003 files. It is supported by Microsoft Excel, LibreOffice Calc, and many other spreadsheet programs. It is different from the newer XML-based .xlsx format and has lower worksheet limits: 65,536 rows and 256 columns.

How to convert WK1 to XLS

Using LibreOffice Calc:

1. Install and open LibreOffice Calc.
2. Select File → Open, choose the .wk1 file, and select the Lotus 1-2-3 import filter if Calc asks which format to use.
3. Inspect the imported worksheet. Check formulas, dates, decimal values, text characters, column widths, and worksheet structure.
4. Select File → Save As.
5. Choose Excel 97–2003 (.xls) or the equivalent Microsoft Excel 97–2003 file type, and save the output with an .xls extension.
6. When Calc warns that some formatting or features may change, confirm that you want to use the Excel 97–2003 format.

You can also convert the file on 101convert.com without installing software: upload the .wk1 file, select XLS as the output format, start the conversion, and download the resulting workbook.

Quality and compatibility limits

Conversion is an import-and-export process, not a perfect format-preserving copy. Lotus-specific formula syntax, macros, external references, charts, print settings, unusual formatting, and unsupported character encodings may be omitted or changed.

Compare important formulas and totals with the original file after conversion. Open the resulting XLS in the software that will receive it, because different applications can interpret imported formulas, dates, and formatting differently.

Keep an unchanged backup of the original WK1 file. If the worksheet exceeds XLS limits or the destination supports newer Excel features, use .xlsx instead; use XLS only when the receiving system requires that older format.