The fastest way to see how much disk space you have left

The df command shows you how much space is used and available on each disk or partition your system has. Run df -h in the terminal to see the results in gigabytes or terabytes instead of raw blocks — the -h flag means "human-readable".

The output shows five columns: the filesystem name, total size, used space, available space, and the percentage used. The "Mounted on" column tells you where that disk appears in your file system. If you see a partition at 95% or higher, that disk is nearly full and may slow down your system.

If you want to see only the filesystems you actually use — not virtual ones the system creates internally — add the -h and -x tmpfs flags together: df -h -x tmpfs. This hides temporary memory-based filesystems that clutter the output.

Key Takeaways

  • The df -h command shows total, used, and available space for each disk in an easy-to-read format.
  • The du -sh command shows how much space a single folder and everything inside it takes up.
  • Run du -sh /home/username/* to see which folders in your home directory are using the most space.
  • A disk above 90% full can cause system slowdowns, and above 95% may prevent new files from being written.

Finding which folders are taking up the most space

The du command measures how much space a folder uses. Run du -sh /path/to/folder to see the total size of that folder and everything inside it. The -s flag gives you a single summary line instead of listing every subfolder, and -h again means human-readable.

To find your largest folders quickly, go to your home directory and run du -sh *. This shows the size of each top-level folder you own. If one folder is much larger than the others, you can run the same command inside that folder to drill down further: cd foldername, then du -sh * again.

If you want the results sorted from largest to smallest, pipe the output to the sort command: du -sh * | sort -hr. The r flag reverses the order so the biggest folders appear first.

Checking a specific partition or mount point

If your system has multiple disks or partitions, df shows all of them at once. To focus on one, run df -h /path and replace /path with any folder on that disk — the system will show you the space for whichever partition that folder lives on.

For example, df -h /home shows the disk that holds your home directory, and df -h / shows the root partition where the operating system files live. This is useful when you have separate disks for different purposes and need to know which one is full.

Understanding the output columns

The df -h output has five columns that tell you different things. The first column is the device name — usually something like /dev/sda1 for a physical disk. The second column is the total capacity. The third is how much is currently used. The fourth is how much is still available. The fifth is the percentage of the disk that is full.

The last column, "Mounted on", shows where that disk appears in your file system. Most of the time you will see / (the root partition where everything lives) and /home (where user files go). If you have external drives or USB sticks plugged in, they will appear here too, usually under /mnt or /media.

Checking disk space without opening the terminal

If you prefer a graphical view, most Linux desktop environments include a disk usage tool. In GNOME, search for "Disks" in the applications menu — it shows a visual breakdown of each disk and how full it is. In KDE Plasma, the "Disk Usage Analyzer" does the same thing and lets you click into folders to see what is taking up space.

These graphical tools are slower than the command line for checking space quickly, but they make it easier to explore which folders are large without typing commands. They also show a visual bar that makes it obvious at a glance whether a disk is nearly full.

What to do when a disk is almost full

If a partition reaches 90% full, your system may start to slow down. At 95% or higher, some programs may fail to write new files. The first step is to find what is taking up space using du -sh as described above, then decide what can be deleted or moved.

Common places to look are your Downloads folder (which often holds old installers you no longer need), your trash or recycle bin (which still takes up space until you empty it), and old log files in /var/log (though be careful deleting these — ask in a Linux community forum first if you are unsure). If you have a .cache folder in your home directory, clearing it is usually safe and can free up several gigabytes.

If you cannot find enough space to delete, you can move files to an external drive or add a new disk to your system. Some systems also support expanding a partition if the underlying disk has free space, but that is a more advanced task.

Frequently Asked Questions

What does "Mounted on" mean in the df output?

It shows where that disk appears in your file system. Most systems have at least a root partition (/) where the operating system lives. If you have a separate partition for your home directory, it appears as /home. External drives show up under /mnt or /media. Every file on your computer is somewhere under one of these mount points.

Is it safe to delete files from my cache folder?

Yes, cache folders are designed to be deleted. Your system will recreate them as needed. The .cache folder in your home directory is usually safe to clear entirely. However, avoid deleting anything from /var/cache without understanding what it is first — some system services depend on those files. When in doubt, ask in a Linux community forum.

Why does my disk show as full when I did not put that much on it?

System files, logs, and temporary files take up more space than you might expect. Log files in /var/log can grow very large over time. Your package manager may also cache old versions of software. Run du -sh /var and du -sh /usr to see if system directories are the culprit, then decide what can be safely removed.

Can I check disk space on a remote computer?

Yes, if you have SSH access to the remote machine. Run ssh username@hostname df -h to see the disk space on that computer without logging in. Replace username with your account name and hostname with the server address. The output appears in your local terminal.