Maximum compression benchmark settings

Goals Test best possible compression settings. Compare top compression formats 7Z, ZPAQ (PeaZip), RAR (WinRar), all formats at best compression settings, in terms of maximum possible compression ratio. 7Z format, always at best available compression level, was also tested replacing the default compresssion algorithm LZMA2 with Brotli, BZip2, and Zstandard algorithms. Software settings Benchmarks are conducted on Windows 10 64 bit, using 64 bit versions of: PeaZip 10.6.0 WinRar 7.11 No cryptography option is set, since encryption impact on performances is out of the scope of this benchmark. Hardware settings Notebook with Intel Core i7-8565U CPU, 4 physical cores with hyper-threading (8 logical cores), 8 GB RAM System disk 512 GB PCIe NVMe SSD, NTFS filesystem. With 7-Zip benchmark score of 23500, this machine represents an entry level specs system for today's standards, especially as tested algorithms are extremely CPU- and RAM- intensive.

Archive formats compared in this benchmark 7Z file format (7-Zip, 1999) Open Source archive format, widely used and well-known for excellent compression ratio, tested using default LZMA2 algorithm Brotli compression algorithm (Google, 2013) applied to 7Z format in alternative to LZMA2 algorithm (in PeaZip, from Advanced tab in compression screen). Brotli is an Open Source pure compression standard developed for maximum compression and decompression speed, but very flexible and capable of also providing high compression ratio. BZip2 compression algorithm (Julian Seward, 1996) applied to 7Z format in alternative to LZMA2 algorithm (in PeaZip, from Advanced tab in compression screen). Based on Burrows–Wheeler transform, BZip2 provides intermediate compression which, in terms of speed/compression ratio tradeoff, is in middle ground between fast algorithms like Deflate and powerful ones like PPMd and LZMA. RAR file format (RarLabs, 1995) proprietary archive format quickly building reputation of being powerful compressor outperforming contemporary zip, bz2, and ace formats. Latest RAR5 format revision is being tested. ZPAQ format (Matt Mahoney at al., 2009) Open Source archive format, computing intensive, providing very high compression ratio, supersedes previous PAQ format, multiple times Hutter Prize winner. The format is now supported through Zpaqfranz implementation. Zstandard compression algorithm (Yann Collet, Przemysław Skibiński, Facebook, 2015) applied to 7Z format in alternative to LZMA2 algorithm (in PeaZip, from Advanced tab in compression screen). Zstandard is an Open Source pure compression standard. Zstd compressor was developed with same scope of Brotli, also very flexible and being capable of deliver high compression ratio in alternative to impressive compression speed.

Max compression / decompression performances test

Maximum compression benchmark methods

Benchmark input data is saved to system disk (PCIe SSD) and compressed to system disk, same partition, separate directory; the resulting archives are then extracted to separate directory on same (system) disk/partition.

Each compression and extraction test is repeated 5 times to get an average value; size is expressed in MB, time in seconds.

Maximum compression benchmark results table, the lower the better for all columns

	Compressed size (MB)	Compression ratio	Compression time (sec)	Extraction time (sec)
WinRar, RAR best	78.1	25.78%	28.5	1.8
PeaZip, 7Z ultra	71.2	23.50%	137.0	3.4
PeaZip, 7Z ultra Brotli	75.1	24.79%	208.0	0.8
PeaZip, 7Z ultra Zstd	75.3	24.85%	300.0	1.2
PeaZip, 7Z ultra BZip2	80.6	26.60%	81.0	7.1
PeaZip, ZPAQ ultra	57.6	19.01%	359.0	358.0

Archive size in MB (lower better), compression ratio of input data, and time in seconds (lower better) to complete compression and de-compression of data.

Maximum compression ratio results

ZPAQ reaches the maximum compression ratio, compressing the 303.0 MB input down to 57.6 MB (19.01%), followed by 7Z ultra (with default LZMA2 compression algorithm) which is able to reduce the input to 71.2 MB (23.50% compression ratio).

Even if usually associated with real-time compression, both Brotli and Zstandard algorithms reaches very high compression ratios (quite close, 24,79% Brotli, 24,85% Zstd), better than BZip2 and RAR, when set at ultra compression level (best possible compresssion settings).

RAR best (WinRar) provides a worse compression ratio than other tested algorithms, with the exception of BZip2.

Maximum compression speed results

RAR best provides fastest compression times of all tested formats.

In the 7Z ultra group, Bzip2 provides the fastest compression, and Brotli and Zstd, set at ultra compression level, takes more time to complete the test than standard LZMA2 algorithm at same compression level, with Zstd being the slowest alternative.

ZPAQ ultra was the slowest compresor in this benchmark.

Maximum compression extraction speed results

7Z ultra, with Brotli and Zstd, provides the maximum extraction speed in this benchmark (Brotli being the fastest).

RAR best is the third fastest extractor, with 7Z ultra with LZMA2 being around 2x slower in decompression than RAR, and 7z ultra with BZip2 being almost 4x slower than RAR.

The slowest format in terms of extraction speed is ZPAQ, with extraction time being in the same range of compression time.
Competing formats, for reference, implement de-compression routines 1 or 2 orders of magnitude faster than compression routines.

Conclusions: best file compressor

Best format for maximum possible compression ratio

ZPAQ ultra is the winner in terms of maximum attainable compression, but is slower than other formats either in compression and, notably, in extraction.

RAR best is the right choice when it is needed to preserve speed at cost of compression ratio (which quite defeats the point of this specific benchmark)

7Z ultra with LZMA2, Brotli, and Zstd, are viable middle ground alternatives to Zpaq, providing significantly slower (but better) compression than RAR best, and preserving resonable (or even faster) extraction times.

What is the most powerful file compressor?

ZPAQ is clearly the top performing format in this benchmark focused on maximum attainable compression.
Zpaqfranz, on the entry level hardware tested in this benchmark, is largely comparable to classic Zpaq implementation in terms of speed and compression ratio when set at ultra compression level, however in the author's repository are available hardware accelerated builds which can improve speed on compatible hardware.

What is the overall best compression format?

It depends on user's need, with compression ratio being only one factor of the equation.
"RAR best" leans on the fast side, "7Z ultra" improves compression ratio at cost of speed, "ZPAQ ultra" is recommended only in case the only factor in account is the max compression ratio.

7Z vs RAR, which is the best compressor?

7Z ultra outperforms RAR best in terms of compression ratio, but RAR outperforms 7Z in terms of compression speed.
Extraction speed is slower, but still reasonable, for 7Z ultra, and can be made faster than RAR using Brotli or Zstd algorithms instead of the LZMA2.Are Brotli and Zstandard suited for max compression?

Brotli and Zstd can provide surprisingly good compression ratios, even if they are designed primarily for fast compression tasks.
Compression effciency seems lower than for LZMA2 algorithm, which produces smaller archives in less time, but extraction speed is better for Brotli and Zstd than for LZMA2.
The two formats tops to very similar max compression ratios, but in this benchmark Brotli outperforms Zstd in terms of compression and decompression speed.

Is it worth to set best / maximum / ultra compression settings?

Increasing compression level decreases performances with diminishing returns: note for reference that compression times in this test are quite similar to ones in the "out-of-the-box" compression benchmark which operates on a 4x larger input!
File spanning and data deduplication are recomended in alternative to trying increasingly higher compression settings, and solid compression option is a must-have to reach highest compression ratio when multiple similar files are involved - even if single files are not compressible (in the traditional sense) one by one.

Read more about how to create 7Z files, how to create PAQ / ZPAQ files, and suggestions if maximum compression is needed.
Please note PeaZip is also capable to create RAR files if WinRar is installed in the system.

Synopsis: Maximum file compression benchmark. 7Z, ZPAQ versus RAR comparison for best, most powerful compressor format. What algorithm compresses the most. What archive format reach highest compression ratio. Which file archiver utility compresses better. What are the best compression options and settings.

Topics: maximum compression benchmark, best file compressor, best archive format for max compression, 7z vs rar vs zpaq

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