Free online BAK to DWG converter

A .bak file may be the only copy available after a drawing was overwritten, damaged, or saved incorrectly, while AutoCAD, a contractor, or a submission system requires a usable .dwg. For an AutoCAD backup, the file usually already contains DWG data; recovery normally requires renaming a copy rather than converting file contents.

What a BAK file is

.bak is a generic backup extension used by many unrelated applications. In AutoCAD, when backup creation is enabled (ISAVEBAK=1), saving an existing drawing normally creates or updates a backup containing the drawing state before that save.

AutoCAD backups are commonly stored beside the source drawing and use the same base name, for example site-plan.bak beside site-plan.dwg. A .bak file from a database, email program, game, or another CAD application is not automatically a DWG file; changing its extension cannot convert unrelated data into a drawing.

What DWG is used for

.dwg is Autodesk AutoCAD's native drawing format. It can store 2D and 3D geometry, layers, layouts, blocks, dimensions, text, references, plotting settings, and application-specific objects.

DWG is used when a drawing must be opened or edited in AutoCAD or compatible CAD software such as BricsCAD, DraftSight, ZWCAD, or Autodesk DWG TrueView. It also supports saving to a specified AutoCAD release when a recipient uses an older CAD version.

Recovering an AutoCAD BAK file

Work on a copy of the backup. Renaming the original can complicate later recovery attempts.

1. Close AutoCAD and any application that may have the drawing open.
2. Copy the .bak file to a separate recovery folder.
3. In Windows File Explorer, enable extensions through View → Show → File name extensions.
4. Rename the copied file from, for example, site-plan.bak to site-plan.dwg.
5. Open the renamed file in AutoCAD or Autodesk DWG TrueView.
6. If it opens, immediately use File → Save As and save it under a new name.

On macOS or Linux, a copied file can be renamed in Terminal with mv site-plan.bak site-plan.dwg.

If AutoCAD cannot open the renamed drawing normally, run the RECOVER command and select the renamed .dwg. RECOVER attempts to open, audit, and repair the file. Use RECOVERALL when the drawing has attached external references that also need checking.

AutoCAD is the preferred repair tool for files created in AutoCAD or Autodesk vertical products. Autodesk DWG TrueView is a free Windows tool for opening the recovered file and using DWG Convert to create an older DWG-version copy. BricsCAD and other DWG-compatible editors can be useful for inspection, but they cannot reliably recover data missing from the backup itself.

Autosave files and online converters

AutoCAD autosave files use the .sv$ extension and can also contain recoverable drawing data. Copy an autosave file, rename the copy to .dwg, then open it or process it with RECOVER. Its location is configured by the SAVEFILEPATH setting. .dwl and .dwl2 files are lock files, not drawings, and cannot be recovered as DWG files.

Online converters are not appropriate for an AutoCAD-created .bak file because no content conversion is required. Many services reject the extension or misidentify it, and uploading drawings can expose confidential plans. Use a reputable desktop DWG tool instead; online conversion is relevant only after confirming that the source is a different, supported CAD format rather than a generic backup file.

Compatibility and recovery limits

Renaming does not alter geometry, layers, object properties, images, or drawing quality. The recovered drawing represents the version before the most recent successful save, so recent changes may be absent.

An invalid-drawing error can mean that the backup is incomplete, corrupt, or not an AutoCAD backup. File size is a useful clue: a backup only a few bytes or kilobytes long is unlikely to contain a complex drawing.

DWG version rules still apply after recovery. A drawing saved by a newer AutoCAD release may not open in an older release; use File → Save As in AutoCAD or DWG Convert in DWG TrueView to save an older version. Custom objects from Civil 3D, Architecture, or third-party applications may require the originating product or its Object Enabler to remain editable after recovery or version conversion.