Guide to 7-Zip Add to Archive Dialog Box

The "Add to Archive" dialog box in the 7-Zip graphical user interface (GUI) is the primary control panel for creating compressed files. It allows users to define the archive's destination, choose compression algorithms, allocate system resources, split files into segments, and apply encryption. Understanding how each setting functions ensures you can balance compression speed, file size, and data security according to your specific needs.

Opening the Dialog Box

To open the dialog box, select one or more files or folders in Windows File Explorer or the 7-Zip File Manager, right-click the selection, navigate to the 7-Zip submenu, and click Add to archive....

Archive Name and Format

  • Archive: Located at the top, this field sets the destination path and file name. Clicking the ellipsis button (...) allows you to browse your directory structure to choose a save location.
  • Archive format: Determines the container format. Options include 7z, zip, tar, and wim. The 7z format provides the highest compression ratios and advanced features, while zip offers maximum compatibility across different operating systems without requiring third-party software.

Compression Parameters

  • Compression level: Offers options ranging from Store (no compression, fastest) to Ultra (maximum compression, slowest). Normal is selected by default and provides a balanced trade-off between time and file size reduction.
  • Compression method: Defines the algorithm used. For 7z, LZMA2 is the default and standard choice. Other algorithms like PPMd (effective for plain text) and BZip2 are also available.
  • Dictionary size: Sets the size of the data block evaluated for recurring patterns. Larger dictionary sizes yield better compression ratios for large, redundant files but require significantly more RAM during both compression and decompression.
  • Word size: Specifies the maximum length of matched byte sequences. Higher values can improve compression on repetitive files at the cost of processing speed.
  • Solid Block size: When enabled (primarily in 7z), multiple files are compressed as a single continuous data stream. This drastically improves the compression ratio for collections of similar small files, though individual file extraction may take longer.

System Resource Allocation

  • Number of CPU threads: Allows you to select how many processor cores or threads 7-Zip can use concurrently. Increasing this number speeds up compression on multi-core processors.
  • Memory usage displays: Two read-only indicators show the estimated RAM required for compressing the archive and the RAM the recipient will need to decompress it.

Options and Archive Management

  • Update mode: Dictates how 7-Zip handles files that already exist in a target archive:
    • Add and replace files: Adds new files and overwrites existing ones.
    • Update and add files: Only updates files that are newer than the ones in the archive.
    • Freshen existing files: Updates older files without adding new ones.
    • Synchronize files: Replaces older files, adds new files, and deletes archived files that no longer exist in the source directory.
  • Path mode: Configures whether 7-Zip stores relative paths, full path names, or flattens the directory structure entirely.
  • Create SFX archive: Converts the output into a Self-Extracting archive (.exe). The recipient can extract the contents on Windows without having 7-Zip installed.
  • Delete files after compression: Automatically deletes the original source files from your drive once the archive is successfully generated.

Splitting Volumes

The Split to volumes, bytes field divides large archives into multiple smaller files. You can enter a custom size or select common presets, such as sizes suitable for FAT32 file limits (4095M), DVDs, or CD-Rs. 7-Zip names split volumes sequentially (e.g., .7z.001, .7z.002).

Encryption Settings

The right side of the dialog box manages password protection and security:

  • Enter / Reenter password: Sets the decryption key for the archive.
  • Encryption method: Typically defaults to AES-256, an industry-standard symmetric cipher.
  • Encrypt file names: Available exclusively with the 7z format, this checkbox encrypts the file directory itself. Unauthorized users cannot view the names or structure of the files inside the archive without first providing the password.