Convert B1 to RAR

A recipient, upload service, or older extraction utility may accept RAR files but not B1 archives. Because the formats are different, conversion means extracting the B1 contents and creating a new RAR archive; it is not a direct byte-for-byte format change.

What the B1 format is

B1 is the archive format used by B1 Archiver, also known as B1 Free Archiver. Its .b1 files can contain multiple files and folders compressed into one archive, with optional password protection. The format is mainly used by people who create or receive archives with B1 Archiver; support in general-purpose archive utilities is less consistent than support for ZIP or 7Z.

Extracting a password-protected B1 file requires its password. A damaged archive may fail during extraction, and conversion cannot repair missing or corrupt data.

What the RAR format provides

RAR is a compressed archive format commonly created with WinRAR. It supports solid compression, password encryption, split volumes, and optional recovery records. RAR5 is the current format, but older extraction programs may support only the older RAR4 format.

RAR is proprietary, so many free tools can extract RAR files but cannot create them. In particular, 7-Zip can usually open RAR archives but does not write RAR archives.

Convert B1 to RAR on a desktop

1. Install B1 Archiver from its official source and install WinRAR if RAR creation is required. Keep enough free space for the extracted files and the new archive.
2. Open the .b1 file in B1 Archiver. Use Extract, select a destination folder, and enter the password if requested.
3. Check the extracted folder. Confirm that all expected files open correctly and that hidden files or nested folders were not omitted.
4. In File Explorer, select the extracted files and folders, then choose WinRAR → Add to archive. Select RAR or RAR5 as the archive format, set a name and destination, and select OK.
5. Use the resulting .rar file for transfer or storage. If the recipient uses old software, select the older RAR format rather than RAR5 when WinRAR offers that choice.

Creating the RAR from the contents of the extracted folder rather than from the folder itself avoids adding an unwanted extra directory level. If that directory level is useful, select the folder instead.

Online conversion

Online archive converters can be convenient for non-confidential files, but B1 input and RAR output are not supported consistently. Use only a service whose current format list explicitly shows B1 as an input and RAR as an output; do not rename .b1 to .rar. Uploading an archive gives the service access to its contents, so desktop extraction and WinRAR creation are preferable for private, copyrighted, or password-protected data.

After an online conversion, download the result and test it with WinRAR or another RAR-capable extractor. Some services silently omit unsupported files, directory attributes, symbolic links, or encrypted content.

Compatibility and data caveats

• Repacking does not preserve the original B1 archive structure, compression settings, encryption scheme, or internal metadata. It creates a separate archive containing the extracted files.
• Compression is normally lossless: file contents do not lose quality. The RAR may be larger or smaller than the B1 archive because the formats use different compression methods and settings.
• File timestamps, permissions, ownership, symbolic links, alternate data streams, and other filesystem metadata may change during extraction and repacking, especially on Windows.
• B1 password protection does not automatically carry over. If protection is required, configure a password and encryption in WinRAR when creating the RAR.
• For large archives, create split volumes only if the recipient or storage system supports them, and transfer every volume with the unchanged names and extensions.
• Open the completed RAR and use WinRAR's Test archived files command before deleting the original B1 archive.