Enable File and Folder Compression?

Enabling file and folder compression in Windows frees up disk space by transparently compressing files, but it can slow down access and is not a substitute for a dedicated archive tool. You can turn it on for a drive, folder, or individual file via the Properties dialog, and the system handles the rest automatically. This article explains how compression works, when it helps, and what to watch out for.

Formula

The calculator above works out your average pace and speed for a run, walk, or cycle. The formula is simple:

Pace (min/km) = Total time (minutes) ÷ Distance (km)

Speed (km/h) = Distance (km) ÷ (Total time (minutes) ÷ 60)

Where:

• Total time – the time you spent moving, in minutes.
• Distance – the distance you covered, in kilometers.

Pace is how long it takes you to cover one kilometer; speed is how many kilometers you cover in one hour. They are two ways of expressing the same effort.

Worked Example

Using the default values from the calculator (50 minutes, 10 km):

1. Pace = 50 ÷ 10 = 5.00 min/km
2. Speed = 10 ÷ (50 ÷ 60) = 10 ÷ 0.8333 = 12.00 km/h

So a 10 km run in 50 minutes gives an average pace of 5 minutes per kilometer and an average speed of 12 km/h.

What Does “Enable File and Folder Compression� Mean?

In Windows, NTFS (the default file system) includes a built-in compression feature. When you enable it on a folder or drive, Windows compresses files as they are written to disk and decompresses them when you open them. This is different from zipping files into a .zip archive – the compression is transparent, meaning you still see and use the files normally, but they take up less space on the hard drive.

The feature is available on NTFS volumes only. If your drive is formatted as FAT32 or exFAT, you won’t see the “Compress contents to save disk space� checkbox. You can check your file system by right-clicking the drive in File Explorer, selecting Properties, and looking at the “File system� line.

How to Enable Compression

You can enable compression on a whole drive, a folder, or a single file. Here’s how:

1. Open File Explorer and right-click the drive, folder, or file you want to compress.
2. Select Properties.
3. Click the Advanced button (on the General tab for a file or folder, or on the General tab for a drive).
4. Check the box that says “Compress contents to save disk space�.
5. Click OK, then Apply. If you’re applying to a folder, you’ll be asked whether to apply to just the folder or to the folder, subfolders, and files. Choose the option that fits your needs.

For a whole drive, you’ll see a similar checkbox on the drive’s Properties dialog. Windows will then compress all existing files and any new files added to that location.

When Should You Use It?

Compression is most useful when you’re short on disk space and you’re dealing with files that compress well – like text documents, spreadsheets, CSV files, and some image formats (e.g., BMP). These files can shrink by 50% or more. Video files, already-compressed images (JPEG, PNG), and executable programs usually don’t shrink much, so you’ll gain little space while still paying the performance cost.

It’s also handy on older laptops with small SSDs where every gigabyte counts. However, if you have a modern, fast SSD and plenty of space, the performance trade-off is often not worth it.

Performance Trade-Offs

Compression uses CPU time. Every time you open a compressed file, Windows has to decompress it; every time you save, it compresses again. On a modern multi-core CPU, this is usually fast, but it can slow down large file transfers, backups, and programs that constantly read and write data (like databases or video editing projects).

On an SSD, the space savings are real, but the read/write speed penalty is more noticeable because the drive itself is already fast. On a traditional hard drive, the reduced data size can sometimes improve performance because the drive reads fewer physical sectors, but the CPU overhead often cancels that out.

Compression vs. Zipping

People often confuse NTFS compression with creating a .zip file. They are different:

• NTFS compression is transparent – you open the file and it works normally. The OS handles compression in the background.
• Zipping creates a single archive file that you must extract to use the contents. It’s portable and works on any system, but it’s not transparent.

If you need to send files to someone else or archive old projects, use a zip file. If you just need to free up space on your own drive and want to keep using the files normally, NTFS compression is a good option.

Common Problems and Limitations

There are a few things that can trip you up:

• Encrypted files can’t be compressed. If you have EFS encryption enabled, the compression option is grayed out.
• Compressed files can’t be encrypted. The two features are mutually exclusive.
• Moving compressed files – when you move a compressed file to a folder that isn’t compressed, it stays compressed. Moving it to another NTFS drive keeps the compressed state. Moving to a FAT32 drive decompresses it automatically.
• System files and some program files – compressing Windows system folders or installed programs can cause errors or slow startup. It’s best to avoid compressing the entire C: drive unless you know what you’re doing.
• Backup software – some backup tools don’t handle compressed files well, and the backup may take longer because the software has to decompress and recompress.

How to Disable Compression

If you change your mind, simply uncheck the “Compress contents to save disk space� box in the same Properties dialog. When you apply it to a folder, you’ll again be asked whether to apply to just the folder or to all subfolders and files. Uncompressing will restore files to their original size, so make sure you have enough free space before doing this.

Frequently Asked Questions

Does compression work on all file types?

No. Text files, Office documents, and uncompressed images compress well. Already-compressed formats like JPEG, MP4, and ZIP files gain almost nothing. You can check how much space you’ll save by looking at the “Compressed size� column if you enable it in File Explorer (View → Add columns → Compressed size).

Will compression damage my files?

No. NTFS compression is lossless – it doesn’t remove any data. The files are exactly the same when decompressed. The only risk is if you delete or corrupt a file, but that’s the same risk as any file.

Can I compress a folder that’s already compressed?

Yes, but it won’t do anything extra. Windows will simply keep the files compressed at the same level. There’s no “double compression� that saves more space.

Does compression work on external drives?

It works on any NTFS drive, including external hard drives and USB flash drives formatted as NTFS. However, if you plug the drive into a device that doesn’t support NTFS (like a TV or game console), you won’t be able to read the compressed files.

Is it better to compress the whole drive or just specific folders?

Usually, it’s better to compress specific folders that contain compressible files. Compressing the whole drive can slow down system performance and cause issues with some programs. If you’re desperate for space, you can try it, but be ready to undo it if things get sluggish.

Does compression affect SSD lifespan?

Not directly. The SSD still writes the same amount of logical data, but because the compressed data is smaller, it writes fewer physical blocks. That can actually reduce wear. However, the extra CPU usage is negligible for modern SSDs.

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in t | Finish time | min | 50 | 0
in d | Distance | km | 10 | 0
out pace | Average pace | min/km | t / d | 2
out speed | Average speed | km/h | d / (t / 60) | 2