TGZ to 7Z Converter

What is TGZ to 7Z Conversion?

Converting TGZ to 7Z means repacking archive contents from a UNIX tarball compressed with the GZIP algorithm into the modern 7Z format that uses LZMA2. The files inside the archive remain unchanged byte for byte; only the container and compression method change. TGZ (TAR + GZIP) appeared in 1992 as the standard way of packaging and compressing data on UNIX systems. The DEFLATE algorithm behind GZIP uses a dictionary of only 32 KB and works in streaming mode, providing high decompression speed at moderate compression ratio. 7Z was introduced in 1999 by Igor Pavlov as part of the 7-Zip utility and applies the LZMA2 algorithm with a dictionary up to 1 GB, delivering significantly tighter compression.

The main reason for converting TGZ to 7Z is the desire to obtain the most compact archive possible. For text data, source code, database dumps, and uniform files, the 7Z format reduces size by 30-60% compared to TGZ. This is especially valuable for long term storage of source code, transferring large document collections, and archiving logs. Another motive is moving from a UNIX oriented format to a universal cross platform one that opens equally well in Windows, macOS, and Linux when the widely available 7-Zip utility or its analogs is installed.

During conversion, the contents of TGZ are first extracted: the GZIP layer is decompressed, then the files are pulled from the TAR container. After that, the original files are packed into a new 7Z archive using LZMA2. File names, directory structure, and timestamps are preserved as far as the target format supports them.

Technical Differences Between TGZ and 7Z Formats

Compression Algorithms

TGZ uses a two layer structure: the TAR container concatenates files into a single stream, and GZIP compresses this stream with the DEFLATE algorithm. DEFLATE combines LZ77 (searching for repetitions in a 32 KB window) and Huffman coding (statistical compression). The archive is compressed as a single continuous stream, which resembles solid mode but does not allow extracting individual files without decompressing all preceding content.

7Z applies LZMA2, an improved version of LZMA that uses a huge sliding dictionary, range coding, and adaptive data analysis. Compression operates on blocks, enabling parallel processing on multi core processors. Additionally, 7Z supports preprocessing filters (BCJ for executables, Delta for audio) that further increase compression density for specialized data.

Capability Comparison Table

Compression Ratio: Real Examples

Archive size ratios for typical data sets:

The advantage of 7Z is especially noticeable on text and uniform data. For already compressed formats (media files, Office documents) the difference is negligible because entropy rich data approaches the theoretical compression limit.

When TGZ to 7Z Conversion is Necessary

Long Term Source Code Storage

Developers often keep program releases, snapshots of git repositories, and archives of older projects. Over several years, savings of 30-50% in size translate into tens or hundreds of gigabytes of free space:

• Historical releases - storing each product version in a more compact form.
• Documentation snapshots - thousands of Markdown files compress much tighter in 7Z.
• Git repository backups - especially repositories with long history and large amounts of text files.
• Educational courses - sets of materials, study guides, and assignments stored more compactly.

Transfer of Large Collections Over Slow Channels

When working through limited bandwidth or mobile internet, every saved megabyte matters:

• Remote workplaces - engineers on business trips receive builds via VPN or mobile connection.
• Regional offices - branches with slow internet receive documentation packages faster.
• Uploading to slow hosting - budget servers with bandwidth limits accept smaller archives faster.

Cross Platform Workflows

TGZ is traditionally associated with the UNIX environment, while 7Z opens equally well on all operating systems:

• Windows and Linux collaboration - mixed development teams avoid having to install special UNIX utilities on Windows machines.
• Sending archives to clients - customers on any platform can open 7Z through common archivers.
• Educational materials for mixed audiences - students with different operating systems receive a unified format.

Log and Backup Archival

Server logs, database dumps, and configuration backups are ideal candidates for 7Z:

• Web server logs - text records compress 10-15 times in 7Z versus 5-7 times in TGZ.
• PostgreSQL and MySQL dumps - SQL statements contain many repetitions ideal for LZMA2.
• Configuration snapshots - sets of YAML, JSON, and XML files compress tighter.

Conversion Process

Transformation Stages

1. Reading the GZIP header - metadata is analyzed: compression method, checksum, original file timestamp.

2. Decompressing the GZIP layer - the DEFLATE algorithm decodes the data stream into the underlying TAR archive.

3. Parsing TAR - records are read sequentially with offsets aligned to 512 bytes, headers and file bodies are extracted.

4. Restoring file structure - file names, access bits, timestamps, and folder structure are reproduced in an intermediate form.

5. Analysis for LZMA2 - the algorithm chooses optimal compression parameters: dictionary size, solid mode, applicability of preprocessing filters.

6. Packing into 7Z - data is compressed by LZMA2 with ultra compression settings. The 7Z header structure is created, metadata and checksums are recorded.

What is Preserved and What Changes

Preserved:

• File names and extensions with Unicode support
• Directory structure of any depth
• File contents byte for byte
• Modification timestamps
• Basic access flags

Changed:

• Final archive size (typically reduced by 30-60% for compressible data)
• Compression algorithm and storage strategy
• Container structure (TAR stream replaced by 7Z block structure)

May be lost:

• Full UNIX owner and group attributes (UID/GID have no direct analog in 7Z)
• Special TAR file types (FIFO, devices, hard links in full form)
• Extended POSIX attributes (xattr)

Comparing 7Z with Other Archive Formats

7Z vs ZIP

ZIP is a standard format with native OS support but weaker compression.

For maximum space savings 7Z is unmatched; for universal compatibility ZIP is preferable.

7Z vs TAR.XZ

TAR.XZ is a modern UNIX format with the LZMA2 algorithm.

Compression ratios are comparable; the choice depends on the environment.

7Z vs RAR

RAR is a proprietary format with similar capabilities.

7Z is preferred as an open and free standard.

7Z Compatibility and Support

Operating Systems

7Z is available on all modern platforms through free programs:

• Windows - the 7-Zip utility is the de facto standard, available since the late 1990s. Versions for x86, x64, ARM64.
• macOS - The Unarchiver, Keka, Bandizip open 7Z. Free apps from the App Store.
• Linux - the standard archiver package is in the repositories of most distributions; supported through GNOME Files, Nautilus, Dolphin.
• iOS and iPadOS - many App Store applications for unpacking 7Z, including free ones.
• Android - file managers (ZArchiver, RAR, Solid Explorer) extract 7Z natively.
• FreeBSD and BSD systems - 7Z archivers are present in the package collection.

Programming Languages

Working with 7Z is supported through libraries in all popular languages:

Format History

• 1999 - publication of the first version of 7-Zip and the 7Z format by Igor Pavlov.
• 2001 - stabilization of the specification, introduction of the LZMA algorithm.
• 2008 - transition to LZMA2 with multithreading support.
• 2010s - widespread adoption as a standard for software distributions and large project packages.
• 2020s - 7Z remains one of the leaders in compression ratio among widely used formats.

Limitations and Alternatives

When Converting to 7Z is Not Optimal

• Archives with specific UNIX attributes - if UID/GID, symbolic links, FIFO channels matter, it is better to stay within the TAR family.
• Very frequent extraction - LZMA2 decompresses slower than DEFLATE; the difference is noticeable when accessing the archive every minute.
• Already compressed media data - the size gain is minimal, using uncompressed TAR is more efficient.
• Environments without 7-Zip - in strict corporate environments where third party software installation is forbidden, ZIP may be preferable.

Alternative Scenarios

• TGZ to TAR.XZ - comparable compression while preserving UNIX habits and POSIX attributes.
• TGZ to ZIP - if native OS support is critical.
• TGZ to TAR - to remove compression and modify the archive contents.

For most scenarios involving long term storage of text data and cross platform distribution of compressible content, 7Z remains one of the best choices thanks to the balance of compression density and availability.