How Much Hard Disk Space is On My Mac?

October 4, 2011, By Christian Cawley

Before you start any backup task on your Mac, or download new information or even install some new software, it is probably worth spending a few moments checking what your current disk capacity is.

After all, as your hard disk drive becomes full, the performance of your computer will decrease. This will impact everything from booting to browsing to running applications and playing games, so being aware of the files that are filling up your hard disk drive and doing something about them will probably come in handy.

Fortunately, once you have identified the types of data that are causing problems you will be able to work out a way of backing these up and removing them from your hard disk drive. The impact of doing this can be seen with one or two particularly useful utilities.

How Much Hard Disk Space is On My Mac?

File Types that Clutter

So what is eating up the space on your hard disk drive? What could be slowing your Mac down so much?

It really depends on how you use your Mac. For instance, if you have an iPhone or iPad, your Mac could become increasingly full of movies and photos that you have recorded on your device, while anyone who likes to download movies or TV shows is going to find that this habit results in available hard disk space being seriously reduced.

Even MP3 files can have some impact, particularly if you have a large library; gaming, too, can have a greater impact than you might expect. Downloadable content or just the usual save games can cause problems for your disk capacity.

Signs That Your Mac Is Full

In order for your computer to normally and to optimum capacity, it requires a generous 10% of free space. Without this, things will start to slow down. This 10% of space is there to keep files tidy, and as the 10% is eaten away at, new data is split up and saved, resulting in the need for defragmentation.

At this stage you will notice a performance hit, caused by your Mac trying to read and write data; if you have a HDD with moving parts rather than a SSD, this will result in a decreasing of the drive’s lifespan.

Things will get worse when your Mac is down to just 1 GB of free disk space. At this stage, you will find that some apps no longer launch without an error message, and as space decreases to the last 100 MB your once super-fast slick Mac will be running slower than a Windows 95 PC.

Checking Hard Disk Usage

Naturally, the way around this is to manage your disk usage more efficiently. The best tool for this is probably DaisyDisk, a utility with a pleasing user interface that illustrates just how much disk space is in use on your computer, and that the various file types that are taking up your disk are doing.

You can download a trial of DaisyDisk from – simply running the app and selecting Scan as Administrator will display a daisy chart representation of your hard disk drive, which you can then use to get a picture of what data is using up the most space, and take action as appropriate.

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