I'm going to share my favorite tools for quickly finding out what's taking up all the space on your hard drive. At TechRoom, I perform dozens of MacBook Pro storage upgrades every week, and one of the most common questions I get is "what's taking up all the space on my hard drive?" This is really important when it's not obvious, like when your Mac shows you a large amount of space being used by "other".

I'll show you how to find out on a Mac, then I'll show you to do the same on PC as well, so if you're using Windows on a Mac, either with Bootcamp or a virtual machine, you'll be able to see where all your storage is going.  If you're a PC user, just use the same tools.

What's using all the space on my mac?

There are two approaches to finding out what's taking up all the space on your Mac.  One approach is to hunt and peck, just looking for folders or going after things based on someone else's experience and advice. This is no fun, it's time consuming and frankly it can be dangerous. The best approach is to use an app designed to show you everything.  That's where GrandPerspective comes in. GrandPerspective is a free utility that graphically shows you what's using your disk space.  Here's what to do:

  1. Download GrandPerspective here
  2. Open the disk image (.dmg) and drag the app to your applications folder
  3. Run GrandPerspective. It will open to a window allowing you to select what you want to scan. Pull down the drop-down menu and select your computer, which is the highest level you can go.  When you do, you'll see your hard drive (or hard drives, if you have more than one).  Select the drive you want to scan, then click scan.
  4. GrandPerspective will scan your entire drive, then present you with a window that shows all the data, color-coded based on one of a few options, and with boxes that represent the relative size of the file or other that's sitting on your hard drive.
  5. You can move your mouse over the files, and GrandPerspective will show you the file name, file path and size of the file at the bottom of the GrandPerspective window.
  6. Want to get to the file quickly?  Just control-click or right click on the file and select "Show in Finder" and GrandPerspective will open up a new Finder window with file or folder right in front of you.

Here's an example I just took, scanning my own MacBook Pro 1TB flash drive:

If you control-click (right click) on anything, you can select "reveal in Finder":

Which will open the finder and present the file, so you can take action, such as copying it elsewhere, throwing it away, etc.:

GrandPerspective is free, and personally, it's my favorite.  It's simple and logical, but maybe not the most intuitive. There's a really good alternative available in the App Store called DaisyDisk (link to App Store) which I think is more intuitive, and definitely fancier with pretty graphics.  DaisyDisk is a lot prettier and more intuitive for selecting a drive to scan, but the interface for finding things is just confusing to me and seems to be way prettier than useful.  That said, it is in the App Store, which is nice for those who want to stay in Apple's somewhat protected ecosystem of apps that are less likely a potential risk for viruses, etc.

What's using up all the space on my PC?

Note: Applies to both PCs as well as Windows on Macs with Bootcamp, VMWare and Parallels

On a PC, the options are, as expected, less elegant, but still practical.  I use Jam Software's TreeSize Free app, which you can find and download here.

In what is classically Windows-esque presentation, TreeSize Free simply calculates the sizes of all folders at the top level of the hard drive, and sorts it from biggest to smallest, top to bottom.  You can expand folders by clicking on the twiddles (that's the technical term for the little arrows for expanding folders).

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