When you want to open a Lotus 1-2-3 spreadsheet in Microsoft Excel, you must first convert the files to the Excel format. Microsoft stopped supporting Lotus spreadsheets in 2007. If you still have access to a computer with Lotus 1-2-3 installed, the simplest solution is to reopen the files and then save them in the Excel format. If you don't have access to the original software, you can also use free spreadsheet applications, such as Gnumeric, Apache OpenOffice or LibreOffice to do the conversion.
Download and install the Gnumeric spreadsheet application (link in Resources). This open-source software is free for anyone to use, and is available for both Windows and Linux. It supports all of the Lotus 1-2-3 extensions, including 123, WKS, WK1, WK2, WK3 and WK4.
Launch Gnumeric and open your Lotus 1-2-3 file. When opening the file, change the file type option from "Spreadsheets" to "All Files," in order to see the filename in the list.
Save the file as an "MS Excel 97/2000/XP" file. This saves the spreadsheet as an XLS file, which you can open in all recent versions of Excel, including Excel 2013.
Download and install either Apache OpenOffice or LibreOffice (links in Resources). These free open-source applications are almost identical, and are available for the Windows, Linux and Mac operating systems. These applications can only open Lotus 1-2-3 files with a 123, WK1 or WKS extension.
Open your Lotus 1-2-3 file. Select "Western Europe" as the character set when prompted.
Save the file as a "Microsoft Excel 97/2000/XP" file. This saves the spreadsheet as an XLS file, which you can open in all recent versions of Excel, including Excel 2013.
Information in this article applies to Microsoft Excel 2013, Gnumeric 1.12, Apache OpenOffice 4.1, and LibreOffice 4.2. Instructions may vary slightly or significantly with other versions or products.