Compressed file formats: which is best in each case

I'm sure you've come across the dreaded warning more than once. “insufficient disk space” or with a huge file impossible to send by emailAlthough today we have hard drives and connections that are much faster than years ago, files have also grown larger: 4K videos, giant games, projects with thousands of files… and compression remains an essential tool.

The problem is that not all compressed formats are the same or serve the same purpose. It's not the same to package a photo folder, compress backups, share documents, or distribute softwareIn this guide, we'll take a calm but concise look at the most commonly used compressed file formats (ZIP, RAR, 7z, TAR, GZIP, BZIP2, ZIPX, ACE, etc.) and explore the best applications for each, drawing on... Real-world tests of compression ratio, speed, resource consumption, and compatibility.

What does a compressed file format actually do?

Before we delve into each format, it's helpful to clarify some concepts. A compressed file format can do two different things (sometimes both): package multiple files into one and compress the data so that they take up less spaceThere are formats that only package (like TAR) and others that package and compress (ZIP, RAR, 7z…).

All these formats are based on compression algorithms, most of them no lossThat is, when you decompress you recover exactly the same bits you had at the beginning. The trick is to find recurring patterns and represent them more efficientlyThe most common ones in this field are Deflate, LZMA/LZMA2, BZIP2, PPMd or variants of LZ77 and Huffman.

When we choose “compression level” (fast, normal, ultra…), we are actually deciding to what extent the program will “rack its brain” looking for patterns: The higher the level, the better the compression ratio, but it increases There and CPU and RAM usageThere are also advanced options such as solid compression or dictionary size that greatly influence the final result.

Finally, in terms of security, many formats allow encrypted with AES (usually AES-256) and password protectionThis is key if you're going to send sensitive information or want to avoid prying eyes in your backups.

ZIP and ZIPX: the universal veteran and its evolution

When someone says "send it to me compressed in zip," practically everyone knows what they're talking about because ZIP has been around since the late 80s and is integrated into almost all OSIt is, by far, the most compatible format.

The classic ZIP format primarily uses the algorithm Deflate, a relatively fast and resource-efficient lossless compression methodThis makes it ideal for everyday tasks: sending a folder by email, packaging a small project, sharing documents with people you don't want to bother with other programs.

Among its key advantages are that The compression and decompression speed is very high, and there is native support in WindowsmacOS, many Linux distributions, iOS y AndroidAlmost any device can open a ZIP file without installing anything, which greatly simplifies life when sharing files with other users.

On the other hand, its compression ratio is not the best on the market: It is clearly inferior to modern formats such as 7z, RAR, or even BZIP2 or GZIP in certain scenarios.However, the most recent versions of ZIP allow the use of AES encryption, significantly improving security compared to the old weak encryption that was easy to break by brute force.

ZIP has a "big brother", ZIPX, which introduced tools like WinZip for achieving better compression ratios at the cost of more time and resourcesZIPX can approach RAR's performance in terms of final size, but it loses much of ZIP's appeal: it's no longer as fast, as lightweight, or as universal.

Therefore, ZIPX only makes sense in specific scenarios: When you want good compression and, due to licensing or company policies, you don't want to use RAR, but you're still within the WinZip ecosystemFor general and shared use, the classic ZIP file is still king.

GZIP, BZIP2 and TAR: the classic Linux and server trio

In environments Unix And in the world of servers, Linux and other very common names appear: .tar, .gz, .bz2 and their combinations .tar.gz and .tar.bz2Although at first glance they may seem like "another type of zip," they actually serve somewhat different purposes.

TAR It doesn't compress anything. Its mission is purely to package: Concatenates multiple files and directories into a single stream with metadata (permissions, dates, paths…), generating the typical .tar file or “tarball”. This philosophy fits with the Unix idea of ​​“do one thing, but do it well”.

Then he enters GZIP at stake. GZIP is a tool and format from the GNU project that uses the algorithm deflate (similar to ZIP) but with a highly optimized implementation. They are often used together: First, the .tar file is created with TAR and then compressed with GZIP, resulting in the well-known .tar.gz files..

GZIP offers a Compression ratio significantly better than classic ZIP, while maintaining very good speed.That's why it's the de facto standard for compressing software packages and files on Linux, and it's also widely used on web servers to compress HTML, CSS, and JS before sending them to the user's browser.

Another important player is bzip2This format, licensed under BSD, It compresses data more than GZIP, achieving a higher compression ratio.But in return, it requires significantly more time and RAM. Like GZIP, BZIP2 only compresses one file, so It is usually seen combined with TAR in .tar.bz2 files.

This makes BZIP2 interesting when You prioritize saving space over speedFor example, in system backups where compression time is not critical. However, for general use, many administrators still prefer GZIP for its balance between speed and file size.

On Linux and macOS, working with TAR, GZIP, and BZIP2 is very natural: They come standard and integrate with graphics file managers and the terminalOn Windows, however, you'll need tools like 7-Zip or WinRAR to handle them without complications.

RAR: the powerful (but proprietary) classic

RAR is another name that has been circulating for decades, especially on Windows. It is a proprietary compression format designed by Eugene Roshal and popularized by WinRARIts code is not free, although there are free tools to extract it on almost any system, such as UnRAR.

Its main attraction is that It offers better compression than ZIP and is very competitive with 7z in many situations, with a good balance between size, speed, and advanced features.It also supports solid compression, where all files are treated as a continuous stream, which greatly improves compression when there are many similar files.

Regarding security, RAR It supports AES encryption (128 bits in many classic implementations) and password protection.Furthermore, it includes a highly valued feature: creation of recovery volumes, which allow repair of damaged files if some sectors of the compressed file are lost or corrupted.

Another historical advantage of RAR has been the ease of split large files into smaller parts (the typical .part1.rar, .part2.rar, etc.), something that has been used a lot to distribute content over the Internet and to bypass size limits on certain platforms.

The downside is that RAR is a proprietary format and WinRAR is paid software (shareware).Although it can be used indefinitely after the trial period (with an annoying warning), it's not always legally or commercially viable. Furthermore, on Linux, to work fully with RAR, you need to install non-free packages like unrar.

Even so, if you're not worried about licensing issues, RAR remains a very solid option for compressing, password-protecting, and splitting files on Windows.especially when you're looking reliability and a very polished set of features.

7z and 7-Zip: the king of compression ratio

If you're obsessed with squeezing every last megabyte of space, then the undisputed star is the format. 7z, used by the 7-Zip program created by Igor Pavlov. 7-Zip is free, open-source software for both personal and commercial use., without ads or cut versions.

The 7z format is designed for offer compression rates far superior to ZIP, RAR and GZIP in most scenariosespecially when you're dealing with data with clear patterns: documents, source code, uncompressed or poorly compressed images, databases of text, etc. It relies primarily on algorithms for this purpose. LZMA and LZMA2, very powerful variants of LZ77 with large dictionaries.

In real-world comparative tests using documents, installers, images, and videos, it is observed that 7-Zip, using the 7z format, produces files that are around 20% smaller than ZIP and significantly smaller than RAR. In many cases. For example, in a test with about 195 MB of varied data, the approximate output was something like this: ZIP around 173 MB, RAR around 166 MB and 7z dropping to about 152 MB, that is, a reduction of more than 22% compared to the original.

However, that extra compression doesn't come free: 7z tends to be slower than ZIP and, in certain settings, even slightly slower than RARespecially in "Ultra" mode. Furthermore, the use of large dictionaries can cause RAM consumption during decompression to skyrocket. A highly compressed 7z file of a few hundred megabytes might require several gigabytes of RAM to extract smoothly.

It has plenty of security: It allows strong AES-256 encryption in both the 7z format itself and ZIP., and supports solid compression, multi-threading (taking advantage of all CPU cores) and a long list of alternative algorithms (PPMd, BZIP2, Deflate, etc.).

Another important advantage of 7-Zip is that, in addition to handling its own 7z format, It opens and extracts virtually anything you throw at it: RAR, ISO, TAR, GZIP, BZIP2, XZ, CAB, WIM, disk images, installer formats, and much more.That's why it has become a kind of "Swiss Army knife" for compressed files.

If you work a lot with compression or want to save as much space as possible without paying for licenses, 7-Zip is the most recommended option as the main tool, both on Windows and on Linux and macOS (via ports or compatible versions).

ACE and other less common formats

Over the years other formats have emerged such as ACE, Stuffit, or some proprietary systems of certain suitesACE was once popular thanks to WinACE, offering better compression than ZIP but falling short of RAR, ZIPX or 7z.

The big problem with ACE and similar formats is that They have not achieved a broad user base or quality free tools to create themIn many cases, only the decompression part was distributed (such as UNACE), and the creation of ACE files was limited to paid or abandoned software.

In practice, this means that It doesn't make much sense to bet on ACE these daysUnless you already have old files in that format and need to extract them. If you need a proprietary format with good compression and real support, RAR makes more sense; and if you want something open and powerful, 7z.

Practical comparison: who compresses more and in what cases

Beyond the theory, what's interesting is seeing how the formats behave when compressing different types of files. Compressing documents, executables, JPGs, or videos is not the same.because each type of data already has its own internal compression or not.

In concrete tests with a mixed set of files (documents, installers, JPG images, videos and PSD files), the results usually follow a clear pattern. For text documents and office applications, 7z with LZMA2 ranks first with the smallest file size., followed closely by RAR (RAR5) and somewhat further behind by ZIP/WinZip. ZIP, integrated into Windows, offers virtually the same result as WinZip in this area.

When we move on to applications and executables (.exe, binaries…), the differences are narrowing7z, RAR, and ZIP achieve similar file sizes, with 7z and RAR edging out ZIP by a few megabytes. In a test set of around 76 MB of applications, all three tools resulted in files that were around 72-74 MB, with 7z slightly ahead.

With JPG images, things change radically. Since the JPG format is already heavily compressed, Adding a ZIP, RAR, or 7z file on top barely reduces the overall sizeIn an example of approximately 42 MB of photos, ZIP and RAR reduced them to around 33 MB, while 7z managed to get them down to about 20 MB thanks to robust compression and aggressive settings, but at the cost of significantly more processing time. In many real-world cases, the difference is between 1-5%, so compression makes more sense for bundling files than for saving space.

With videos in modern formats (MP4, MKV with H.264, H.265, AV1 codecs…), the story is similar: The file is already brutally compressed and you can barely squeeze out a few megabytes.In a batch of about 66 MB of clips, ZIP was around 59 MB, RAR around 55 MB, and 7z around 54 MB. There are savings, but they're not spectacular.

In heavy working files such as Photoshop documents (.psd), where there are layers and less internally compressed data, 7z regains a clear advantageFor example, from the original 3,64 MB, you could reduce it to ~1,37 MB with 7z, while RAR was down to ~1,56 MB and ZIP to just over 2 MB.

If we look at the entire test set (about 195 MB mixing everything), the overall picture is clear: ZIP reduces by about 11%, RAR by about 15%, and 7z by around 22%.In other words, globally, 7-Zip achieves files approximately twice as efficiently as conventional ZIP files.

Key factors: speed, resources, and memory when decompressing

When discussing "which format is better," almost everyone only looks at the compression ratioBut it's important not to forget speed and resource consumption when compressing and, especially, when decompressingThis is where sometimes "Ultra" stops being a good idea.

Powerful algorithms like LZMA2 use large dictionaries: They store structures in memory to make the most of data patternsThis means that compressing and decompressing with aggressive settings requires a lot of RAM. On a machine with 8 GB or less, trying to extract a 7z file compressed in "Ultra" mode can slow down the entire system and even cause crashes if memory is insufficient.

Instead, Traditional ZIP and GZIP are quite lightweight in terms of resources.They work very well on modest systems, on loaded servers, and on mobile devicesThis is one of the reasons why they are still used so much, despite not offering the best compression ratio in the world.

RAR finds itself in an interesting middle ground: It offers good compression with very competitive speed and reasonable CPU and RAM usage.In many comparisons, WinRAR is slightly faster than 7-Zip in its default settings, although it leaves somewhat larger files.

Therefore, when you are going to share a file with someone and you don't know what kind of computer they have, Sometimes it's more sensible to use a "Normal" or "Fast" compression level, or to use standard ZIP.You'll save yourself a lot of trouble if the other person opens the file on an old laptop or a PC with limited memory.

Another factor is the type of compression: Solid compression greatly improves file size when dealing with many similar files, but it worsens access speed and amplifies damage if part of the file becomes corrupted.It's a fantastic option for long-term archiving, but less ideal if you're going to frequently modify the contents of the compressed file.

Which format to use depending on your case

With all of the above, it is clear that there is no "magic" format that is the best at absolutely everything. The choice depends on what you're going to do, who you're sharing the files with, and the hardware availableAs a practical guide:

If your top priority is Make the most of the space and don't mind waiting for something moreThe sensible thing to do is choose the 7z format with 7-Zip, using a high compression level and, if necessary, solid compression. Ideal for personal backups, archiving projects, or packaging large collections of documents.

If you're looking for A balance between speed, compression, and advanced features such as file repair and volume splittingRAR (with WinRAR) remains a very good option, especially on Windows. It's perfect for robustly distributing software, games, or large data packages.

To for occasional use or when compatibility is paramount (sending files to non-technical people, sharing material in mixed environments, etc.), the most convenient option is to stick with ZIP, using the built-in compressor in Windows or macOS. It's fast, simple, free, and anyone can open it.

In Linux environments, servers and development, TAR + GZIP (tar.gz) remains the de facto standard for distributing code, packages, and backups. When a little more compression is needed and time isn't critical, TAR + BZIP2 (tar.bz2) comes into play as an alternative.

Regarding specific tools, if you frequently work with compressed files, 7-Zip and PeaZip are two highly recommended free options.7-Zip stands out for its power and minimalism, while PeaZip offers a more modern interface and support for over 200 different formats. WinRAR, meanwhile, remains the go-to if you want to work extensively with RAR files.

And if you only handle compressed files once a month to send four documents, What comes with your operating system (native ZIP) is more than enough.You don't need to install anything else unless you receive RAR, 7z, or other less common file formats.

Given the whole picture, the key to success is not to stick to a single format, but Be clear about what you prioritize in each situation: compatibility, space saving, speed, or extra featuresFrom there, choosing between ZIP, 7z, RAR, TAR+GZIP or BZIP2 becomes much simpler and you will stop compressing "blindly" and start using the appropriate tool in each case.