How to Resize Partitions on Mac OS X El Capitan

Being well organized doesn’t have to be limited to work and life, it can be applied to computers too. I found myself extremely messy at managing my Mac files. Many times, I have to find a file, a question always pops up in my mind: where the hell did I save it?

Why that always happens to me? I’m not well organizing my Mac data. More specifically, I am used to keeping everything in one partition. So, here’s the trick – resizing or adding a partition helps.

Today, I’m going to show you how to resize a Mac partition under OS X El Capitan.

Is it safe to resize a Mac partition?

Well, I’d say it’s relatively safe (not 100% though). Why is that? Because your Mac probably has only one partition, and it’s the main boot volume. Resizing mounted boot partition is not the best idea no matter what computer or operating system you use. Since all your operating system files store in that partition, a tiny misoperation could go wrong and cause data loss – the worst thing you’d ever want to happen.

So, what should you do first?

Backup! Though it’s an old term that has been over-emphasized in the Mac world, still I’d strongly recommend you backup your data before proceed. The easiest way is to use Time Machine. This Apple support article has more.

Resizing Mac partition using Disk Utility

Step 1: Open Disk Utility. In Spotlight search box, type “Disk Utility” and double click on the first result that shows.

Step 2: Select the Mac hard drive you want to partition, click the “Partition” icon (next to “First Aid”). Now navigate the circle to adjust the size you want, and hit “Apply” button to continue.

Step 3: Wait for the process to complete. Done.

You can also watch this video for how:

If you have installed Boot Camp (Windows) on your Mac

Chances are that you also have Windows 10 (or 8, 7) run on your Mac, besides the main OS X El Capitan. In this case, you won’t find Disk Utility useful. But still, it’s doable with a third-party Mac partition manager.

One last reminder – before you proceed, make sure you have backed up important files or the entire drive, just in case.

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