(I released during a long period where OmniDiskSweeper wasn't available, it is, again), so if you'd like to try my take on this, check out SimplyDiskSweeper

This is the second post of a series of articles on reducing disk space usage on your Mac. Read the first post, Reducing Disk Usage on Your Mac by Processing Your Videos if you haven’t.

If you want to know how to use OmniDiskSweeper on a Mac, the short version is: download it, scan your disk, open the biggest folders, and delete only files you understand.

In order to reduce disk usage, you need to know what is unnecessarily using up disk space. OmniDiskSweeper from The Omni Group is great for figuring this out. Download OmniDiskSweeper directly here.

Running OmniDiskSweeper

OmniDiskSweeper drive list

Launch the app and it’ll show you a list of drives. Chances are the first entry will read “Macintosh HD”. That is your hard disk/SSD. Double click on it to start scanning your drive contents. If you have multiple hard disks or have external disks attached, you will see more than one entry.

OmniDiskSweeper scanning a disk

Subject to the size and type of your disk, OmniDiskSweeper should take at least a few minutes to run. While it’s running, the title bar will say it’s “sizing” and you’ll see that the numbers besides each directory have different colors. The numbers indicate how much space the directory is taking up, with a still-scanning number indicating that directory is still being scanned.

OmniDiskSweeper folder sizes

Once the app is done (the word “sizing” will no longer be shown in the title bar). In the screenshot above, you’ll see that in my case, the /Users directory is taking up a whooping 172.6 GB of my hard disk. That can present some good opportunity for clearing up my disk. You can browse around by clicking.

OmniDiskSweeper Downloads folder size

For illustration purposes, let’s say I want to delay cleaning of my Pictures and Documents directories for the time being. Taking up 5.8GB, the Downloads directory is low hanging fruit. Since this is where the Mac saves downloaded files, I double-click it the directory – opening Finder – and verifies that there isn’t any file that I want to keep. I then empty the entire Downloads directory.

Repeat this process for the bigger directories that aren’t managed by the system (such as Library) and you’ll be able to trim a lot of fats from your drive.

Is OmniDiskSweeper free?

Yes. OmniDiskSweeper is a free Mac disk usage utility from The Omni Group. It scans folders and shows what is taking up space, but it does not decide what should be deleted for you.

What is safe to delete?

Start with folders you own and understand, such as Downloads, old archives, exported videos, disk images, and duplicate installers. Be careful with system folders, application support folders, photo libraries, and anything in ~/Library unless you know exactly what the files are for.

If you want a simpler app for the same job, I also made SimplyDiskSweeper.

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