.BK1 File Extension

A .BK1 file is a ERwin Backup File, created by Autodesk.

Open with Autodesk AutoCAD 2023. Available for Windows.

What is a .BK1 file?

A .BK1 file is a type of backup file used by Autodesk software, which includes programs like AutoCAD Mechanical, Mechanical Desktop, and AutoCAD Map. This file is actually a .BAK file that has been given a new name with the ".bk1" extension. This renaming happens when an Autodesk program closes down unexpectedly, like during a crash.

When you work on drawings in these Autodesk programs, the software automatically makes a .BAK file every time you save your work. This .BAK file is a backup of your drawing, so if something goes wrong, you won't lose all your work. However, if the program crashes, there's a risk that the .BAK file could be corrupted. To prevent this corrupted backup from overwriting the good backup, the Autodesk application changes the .BAK file's name to .BK1. This way, your original backup is safe.

You can open .BK1 files with Autodesk AutoCAD 2023 or Autodesk AutoCAD Mechanical 2023. These programs recognize the .BK1 file as a backup and can use it to restore your work.

It's worth noting that if a .BK1 file already exists when the program tries to rename a .BAK file, it will instead use extensions like ".bk2" to ".bk9", and then ".bka" to ".bkz", and even ".baa" to ".bzz". The program keeps trying new extensions until it finds one that hasn't been used yet, ensuring every backup is kept separate and safe.


Our goal is to help people find the most up-to-date information about file extensions for Windows, Mac, Linux, Android and iOS. We researched over 10,000 file extensions and their respective programs that open those files. If you want to suggest edits or updates about .BK1 file formats, example files, or programs that are compatible. Please contact us.

More extensions