Excel Can't Open Your Lotus 1-2-3 Files Anymore

Lotus 1-2-3 was the spreadsheet that built the PC business world in the 1980s and early 90s. If you have inherited accounting records, budgets, or research data from that era, they are probably sitting in .wk1, .wk3, .wk4, or .123 files — and modern Excel will not open them.

Why Excel gives up on these files

Microsoft removed the built-in Lotus 1-2-3 file converters beginning with Excel 2010. Newer versions do not include the import filter at all, so double-clicking a .wk4 file produces an "unrecognized format" error or a screen full of garbled characters.

• Excel 2010 and later cannot open .wk1, .wk3, .wk4, .wks, or .123 files.
• The old "lmbcs" and translation add-ins were discontinued.
• Renaming the file to .xls does not work — the underlying binary is different.

Convert the worksheet, keep the data

LegacyFileConverter reads the original Lotus binary directly and rebuilds it as a modern spreadsheet. Choose XLSX to keep cells, columns, and basic formatting for use in Excel or Google Sheets, or CSV if you only need the raw values for import into another system.

Summary

Lotus 1-2-3 data is not lost — it is just locked in a format Excel abandoned. Convert it to XLSX or CSV once and your decades-old spreadsheets become living documents again.