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

Games have been getting big, with some coming in at more than 100GB in size. If you’re limited on storage space, you don’t typically have many options. You can uninstall some of your least-played games, but if you don’t have a fast internet connection, that can still be frustrating. You could also invest in more storage or even external storage, but that can be expensive, you might be limited on slots, or it might be slower. There’s another, free tool that can help you, though: CompactGUI.

CompactGUI has been around for quite a long time, and has given rise to paid alternatives like “CompressorX”, which does the same thing while claiming to be “AI-powered”. CompactGUI is older, it’s free, and it’s open-source, though some users prefer Compactor instead. You can use either, as they both do the same thing. In some extreme cases, like the 169GB ARK: Survival Evolved, the game’s size can be reduced to 91.2GB, nearly halving the storage used. While other games may not have such big benefits, it’s a great way to reclaim a few gigabytes here and there, and in extreme cases, you might reclaim a lot ​​​​​​of space.

As well, CompactGUI works on both programs and games, and the results in programs can be impressive, too.

How does CompactGUI work?

It’s transparent compression

CompactGUI isn’t actually doing anything special when it comes to compressing your games, and that’s exactly why it’s so good. It uses compact.exe, a built-in Windows tool, that can transparently compress files that are stored on an NTFS-formatted partition, the default partition format for Windows PCs. “Transparent” compression means that the files themselves are still usable in the same way that they would have been before, and they aren’t repackaged as another format.

These algorithms, listed in order from the fastest and smallest compression ratio to the slowest but best compression ratio, are the following:

• XPRESS4K
• XPRESS8K
• XPRESS16K
• LZX

The “K” refers to the block size, meaning that XPRESS4K uses a 4K block size, for example. LZX uses 32KB blocks, which offers better compression at the expense of more CPU overhead. That’s the other side of the coin when it comes to CompactGUI, though, as the files are still decompressed in RAM in order to be used. That means your CPU has to use some clock cycles just for decompressing game assets.

In most cases, it’s not that performance itself will be affected, but rather your loading times may be. With that said, better compression ratios may result in improved loading times when playing games from an HDD, as the smaller files are able to be read faster than they would have been before. I’ve compressed most of my games, and I haven’t noticed any downsides in performance or load times as a result, but your mileage may vary.

How much does CompactGUI reduce the size of your games?

Quite a lot, in some cases

CompactGUI retains a large database of games, with their original sizes, the final size, and the compression type used. This database is in a JSON object, and not every game has data from every compression ratio. I parsed this data locally and exported it to a CSV, and while you may not have the exact same results when using CompactGUI as shown here, it should be close to the final result. These stats are automatically submitted by CompactGUI to the database.

We’ll go through some games, with the first being the stats from Cyberpunk 2077.

These results aren’t particularly impressive overall, but a gigabyte or two here and there can add up, especially when considering that it’s free storage that you’re getting back. This also indicates that the game is already compressed efficiently, as you won’t get good results from already-compressed files. Now we’ll look at a game with significantly bigger savings, Baldur’s Gate 3.

In this case, we’re looking at a minimum ​​​​​​of 10GB ​​​​​​of space savings, which is pretty impressive. Even with the lightweight XPRESS4K compression type, that’s 12GB reclaimed for free. That space can be enough to hold a whole extra game! Finally, we’ll look at Counter-Strike 2.

As you can see, the difference can vary wildly, and you’ll get back a decent amount of space when it comes to Counter-Strike. Finally, I have cherry-picked some other interesting games that I saw in the database. Some games, as you’ll see, benefit hugely from compression.

While not every game benefits from massive storage reductions when using the compact tool, the ones that do can save you a huge amount of storage space compared to the game’s original size. In the case of Little Kitty: Big City, you’re getting back more than half of your storage, and the same goes for Cities: Skylines when using LZX. Even with Half-Life: Alyx, you’re getting back between 10 and 14GB, which is pretty sizeable.

With CompactGUI, you’ll need to watch out for game updates. It has a watchlist built in that can monitor your game folders, and when an update is detected, it can automatically compress the new and changed files for you. Finally, you shouldn’t use this on games that use DirectStorage, such as Ratchet & Clank: Rift Apart. This is because the assets will need to be decompressed by your CPU rather than being streamed to your GPU, negating any performance gains of DirectStorage.

Should you use CompactGUI?

Why not?

To be honest, I don’t see why anyone wouldn’t use it. It’s a free tool that gives you back space on your PC. For gaming handhelds, it can be fantastic, and I’ve seen people using it to compress their library of emulated games with fantastic results. Plus, if you find yourself struggling for space on your PC, it can also be a lifeline at times when you just need a few more gigabytes.

Give it a try, and if you find it impacts performance, you can always decompress your files the same way you compressed them in the first place.