Software & Apps File Types What Is an XLK File? How to open, edit, & convert XLK files By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated March 24, 2020 File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More Tweet Share Email A file with the XLK file extension is an Excel Backup file created in Microsoft Excel. An XLK file is just a backup copy of the current XLS file that's being edited. Excel creates these files automatically in case something goes wrong with the Excel document. If, for example, the file is corrupted to the point that it can't be used any longer, the XLK file acts as a recovery file. XLK files may also be created when exporting information from Microsoft Access into Microsoft Excel. The BAK file format is another backup file used in Excel. How to Open an XLK File XLK files are most commonly opened using Microsoft Excel, but the free LibreOffice Calc program can open them, too. If your XLK file doesn't open in either of these programs, be sure that you're not confusing it with a file that has a similar extension. There's more on that at the bottom of this page. Your XLK file is most likely an Excel Backup file, but something else you can try to see if it's in a another format is to open it with a free text editor. Even if the file isn't readable/usable, you'll be able to see if there's any text within it that might help you determine what program was used to build it, which might lead you to a compatible file opener. If you have more than one program installed that supports XLK files, but the one that's set to open these files by default isn't the one you'd like, see our How to Change File Associations in Windows tutorial for help changing it. How to Convert an XLK File Opening an XLK file in Excel is just like opening an XLS file, which means you can use Excel's File > Save As menu to convert the file to XLSX or any of Excel's other formats. LibreOffice Calc supports some of the same formats as Excel. You can convert an XLK file in LibreOffice Calc by opening the file and then using the File > Save As option. An XLK file can also be converted to PDF with Calc's File > Export menu. More Information on XLK Files You can enable Excel backups on a per-document basis. When you go to save your XLS file to a specific folder, but before you actually save it, go to Tools > General Options. Then just check the box next to Always create backup to force Excel to keep a backup of that specific document. XLK files are really a version behind the current one that you've saved. If you save the file once and enable the backup, the XLS and XLK file will be saved together. But if you save it again, just the XLS file will reflect those changes. Save it once more and the XLK file will have the changes from the first and second save, but only the XLS file will have the most recently saved edits. The way this works means that if you make a bunch of changes to your XLS file, save it, and then want to revert back to the previous save, you can just open the XLK file. Don't let that all confuse you. For the most part, XLK files pop in and out of existence automatically and help to make sure you don't lose your data if something unfortunate happens to the open file. Still Can't Open the File? If the file isn't behaving well with Excel, you might have a file in a totally different, unrelated format. This can happen if you've misread the file extension as XLK when really it's something just spelled similarly. For example, an XLX file has nothing at all to do with Excel. If you try opening one in Excel, you'll get an error. On the other hand, a number of other file types are used in Excel, and they, too, look very similar to XLK: XLB, XLL, and XLM are a few. They work with Excel just fine, so confusing one of those for an XLK file isn't actually an issue.