Shrink Game Sizes on Windows with CompactGUI: Free Space-Saving Made Easy

As game sizes continue to balloon, with some modern AAA titles tipping the scales at more than 100GB, the anxiety over dwindling disk space is becoming all too common for PC gamers—especially those who game on laptops, smaller SSDs, or budget builds. The traditional answers have always been to uninstall games, buy more storage, or shuffle lesser-used titles to slower disks or external drives. These solutions, however, come with their own headaches: slow re-downloads, real money spent on new hardware, or the frustration of juggling files across devices. What if instead, you could simply shrink the games you have, reclaiming space without sacrificing performance? The free and open-source tool CompactGUI is emerging as a surprisingly effective answer, and it’s gaining renewed attention in the age of behemoth installs and increasingly precious gigabytes.

CompactGUI: The Storage Saver Hiding in Plain Sight​

CompactGUI isn’t a new entrant, but its relevance is undoubtedly growing. Built as a graphical interface to harness Microsoft’s native compact.exe command-line tool, CompactGUI lets users compress folders on NTFS drives with just a few clicks. Unlike basic “zipping” or proprietary compression schemes, this approach takes advantage of Windows’ transparent compression, leaving files in their original place, format, and usable state. Applications and games can load exactly as before, and the process is reversible at any time.
While more sophisticated, paid alternatives have surfaced—such as “CompressorX,” which touts “AI-powered” improvements—CompactGUI remains completely free and open-source, making it an attractive option for those who don’t want their storage optimization behind a paywall or dependent on closed, proprietary tech. For power users, tools like “Compactor” exist for similar tasks, but CompactGUI’s simple design and active user community make it an appealing starting point, especially for less experienced users.

How Does It Work? Under the Hood of Transparent Compression​

At its core, the solution is elegantly simple: CompactGUI is a wrapper around compact.exe, a utility that’s built into all modern versions of Windows (from Windows 8.1 onward). This leverages the NTFS (New Technology File System) feature that allows entire folders or drives to be transparently compressed using one of several algorithms:

• XPRESS4K
• XPRESS8K
• XPRESS16K
• LZX

The numbers refer to block size—larger blocks usually mean better compression but more CPU usage when accessing the file. LZX, with a 32KB block, provides the most compression but comes at the cost of higher CPU usage when the file is accessed, while XPRESS4K is the fastest but compresses the least. The result is a spectrum: you can prioritize maximum space savings, minimum processing overhead, or a balance in between.
Unlike traditional archive tools, Windows handles these files exactly as it does any other—there’s no need to unzip, open special software, or change your workflow. The operating system decompresses the file’s data on the fly when it’s read, keeping the process invisible to the user. Storage is saved without changes to file organization, shortcuts, or compatibility (with one important caveat, discussed later).

Real-World Results: From Modest Savings to Massive Gains​

The effectiveness of CompactGUI ultimately depends on the source material. Some games, especially those with lots of relentlessly compressed assets (like videos or high-fidelity textures that are already in efficient formats), may only yield slight improvements from NTFS compression. Others, particularly those loaded with uncompressed or poorly compressed assets, can see storage cuts of 30%, 50%, or more.
The publicly available CompactGUI database, which aggregates real-world experiments from users, paints a nuanced but hopeful picture:

Cyberpunk 2077​

Compression Type	Original Size	Compressed Size	Compression Ratio
XPRESS4K	79.95GB	78.26GB	0.98x
XPRESS8K	78.78GB	77.61GB	0.99x
XPRESS16K	77.46GB	76.04GB	0.98x
LZX	80.2GB	78.25GB	0.98x

Here, the savings are modest—roughly one to two gigabytes reclaimed. This suggests that Cyberpunk 2077’s installation is already aggressively compressed, so there’s little left to squeeze out.

Baldur’s Gate 3​

Compression Type	Original Size	Compressed Size	Compression Ratio
XPRESS4K	142.62GB	130.78GB	0.92x
XPRESS8K	146.18GB	129.92GB	0.89x
XPRESS16K	145.9GB	129.78GB	0.89x
LZX	152.71GB	134.54GB	0.88x

With LZX, that’s over 18GB saved—enough free space to install another moderate game. Even the “fast” mode returns 12GB, and for users with storage constraints, that’s substantial.

Counter-Strike 2​

Compression Type	Original Size	Compressed Size	Compression Ratio
XPRESS4K	39.44GB	29.34GB	0.74x
XPRESS8K	36.18GB	26.28GB	0.73x
XPRESS16K	37.73GB	28.13GB	0.75x
LZX	38.17GB	27.04GB	0.71x

Counter-Strike 2 gets the largest boost in this sample: over 10GB saved, or about a 25–30% reduction. That’s transformative on a smaller drive.

Outliers With Major Savings​

A few titles are standouts, illustrating the best-case scenario:

• Little Kitty: Big City: 13.76GB compressed to 6.34GB (XPRESS16K), or 5.44GB (LZX)—savings of over 50%.
• Cities: Skylines: 13.06GB down to 7.08GB (XPRESS16K) or 6.3GB (LZX)—again, nearly halved.
• Half-Life: Alyx: 72.93GB to 61.6GB (XPRESS16K) or 58.08GB (LZX)—10–14GB savings.

It must be stressed: not all games will benefit this dramatically. Games that are already packed with compressed formats have little left to give; for these, results may be similar to those seen with Cyberpunk 2077. The variability—sometimes even within genres or publisher portfolios—can be dramatic.

Performance Impacts: Theory, Evidence, and User Experience​

A core anxiety for anyone considering space-saving measures is performance loss. If your painstaking efforts to reclaim free space lead to higher CPU usage, stutter, or longer loads, the trade-off may not be worth it. Fortunately, the evidence points to largely negligible performance impacts for most use cases:

• Typical usage: For the vast majority of games, especially on modern CPUs, users report little to no frame-rate drop or additional stutter during actual gameplay.
• Loading times: In rare cases, especially when playing from an SSD, load times might even improve slightly, as smaller files mean less data to read from disk before decompression. This effect is more pronounced on slower HDDs, where the bottleneck shifts from disk to CPU.
• Heavy compression (LZX): Choosing the most aggressive compression could theoretically drag down performance on weak CPUs or with games with high I/O (many small file reads). However, in user testing and community reports, this impact is almost always minimal—benchmarked differences are typically within the margin of error for most titles.

Crucially, some scenarios should be approached with caution. For example, games designed for Microsoft’s DirectStorage technology (currently a minority, such as “Ratchet & Clank: Rift Apart”) could see worse performance or break entirely if NTFS compression is used. DirectStorage streams assets directly from disk to GPU, sidestepping the CPU decompression routine. Compressing these files, therefore, mitigates or reverses the benefits. CompactGUI itself warns against its use for these specific titles.
Ultimately, for classic game installs, emulated libraries, or titles that don’t push storage subsystems in new, experimental ways, CompactGUI is widely reported to be safe. And if trouble is encountered, decompressing files is just as simple as compressing them.

Ease of Use, Automation, and Practical Tips​

For those intimidated by Windows’ command line, CompactGUI provides an easy, clear interface. Just select the folder (game, app, or otherwise), pick a compression algorithm, and click a button. A real-time status panel updates progress, and with a well-ordered UI, the whole process feels accessible, even to newcomers.
Key user-friendly features include:

• Automatic update monitoring: CompactGUI can watch folders for additions or changes due to game updates. Whenever new or altered files are detected, it can reapply compression without user intervention.
• Reversibility: Any compressed folder can be decompressed at any time. No permanent changes are made, and files remain in the original structure.
• No repackaging necessary: The application does not “repackage” or alter file types, so there’s no compatibility risk with future patches, mods, or system restores, barring the exceptions noted above.

Pro tip: It’s wise to back up important saves or configs before testing, although data loss or corruption is extremely uncommon with native NTFS compression. For those curious or cautious, start with small, low-stakes folders to gauge the effect.

Competitive Landscape: Free vs. Paid, Open vs. Proprietary​

While alternatives like CompressorX have entered the scene with bravado—promising “AI-powered” compression—there’s skepticism about actual material gains over the tried-and-true NTFS methods. CompressorX and similar paid tools often offer more polish or “one-click” workflows, but CompactGUI’s open-source nature, transparency, and free price point are massive strengths.
Some users may consider “Compactor,” another open-source front-end, which is slightly more technical but similarly built around compact.exe. For most, CompactGUI strikes a strong balance, providing an accessible path to effective NTFS compression.
It’s worth underscoring: no tool fundamentally “invents” new compression methods here. All rely, in the end, on built-in Windows algorithms and OS support, not proprietary formats. This means that the risk of vendor lock-in or file incompatibility is minimal—files stay readable and usable, even if you move them to a different PC running Windows.

A Noteworthy Community and Transparency​

One of CompactGUI’s subtle advantages is its open and visible community. User results (including before/after file sizes by game and algorithm) are collected and available for public perusal, lending both credibility and transparency to the process. If you’re skeptical, you can check statistical aggregates—seeing which titles offer real benefit, and which don’t. This dataset also helps highlight edge cases, such as games where compression is either spectacularly effective or modest at best.
Community reporting also means frequent updates and bug tracking—a luxury seldom found in purely commercial, closed-source offerings.

Risks, Limitations, and What Not to Compress​

While CompactGUI is generally safe, there are some caveats worth explicit note:

• DirectStorage games: As mentioned, modern games leveraging DirectStorage may lose their performance edge or even malfunction if compressed. Always check before applying compression; game-specific forums and CompactGUI’s database are great resources.
• Aggressively compressed games: Titles already packed with high-efficiency archive types—such as many AAA games—will see little change. Attempting to squeeze more savings may even slightly increase load times, as more CPU cycles are spent for almost no gain.
• Frequent updates: Some MMOs and “live service” games patch very frequently; automatic re-compression is helpful, but it’s an added maintenance step to remember.
• Legacy devices: On older CPUs or very weak systems, aggressive compression may introduce small delays when opening highly compressed files, though this is rarely an issue on hardware from the last decade.

The best defense against disappointment is to check the CompactGUI database before compressing, especially for lesser-known titles or novel game engines. For most popular games, results are well documented.

Use Cases Beyond Gaming: A Win for Apps and Emulated Libraries​

While most coverage focuses on big-name games, the utility of CompactGUI extends further. Applications, datasets, and especially emulation libraries often see tremendous benefit. ROM sets, uncompressed ISO images, and older programs (pre-2010) can sometimes be halved in size, dramatically stretching SSD or SD card space on handhelds and vintage laptops.
CompactGUI can also be a boon to archivists, modders, or anyone curating a large, static collection of files that don’t change every week.

Should You Use It? Weighing the Evidence​

Given its free cost, reversibility, and reported effectiveness, CompactGUI is worth a try for virtually every Windows gamer or PC enthusiast worried about disk space. It won’t always deliver dramatic results, and it’s essential to be aware of the (few) exceptions and edge-case warnings. However, its accuracy, transparency, and community backing—combined with the power of native Windows compression—make it a low-risk, high-reward prospect.
For those on gaming handhelds, or with big emulated libraries, it might be nothing short of transformative. Many users report compressing entire libraries without notable downside, gaining dozens—or even hundreds—of gigabytes in the process.
If, for any reason, you notice an impact on game performance or encounter problems, decompressing is as simple as clicking a button—the process is fully reversible. As always, monitor essential folders, stay aware of DirectStorage-powered titles, and enjoy stretching your storage further than you thought possible.

Final Thoughts​

As digital game sizes climb, the need to fight back with smarter, safer, and more user-friendly space-saving tools is more important than ever. CompactGUI—free, open source, verifiably trustworthy, and built on features Microsoft itself supports—is one of the best tools available. Whether you’re running out of space or just want to keep your drives lean for maximum longevity and performance, this tool deserves a place on your shortlist.
For the cost of a download and a few minutes, your expanded library, smoother workflow, and healthier SSD might just thank you.

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Source: XDA I use this free, open-source tool to significantly compress my games on Windows without any performance loss