How to defragment a Mac

Slow Mac? Defragging a Mac’s hard drive is a great way to speed up and add life to a slow or aging computer. However, when it comes to defragging a Mac, the situation gets complicated. Recent versions of the Mac operating system are designed to take care of the problem automatically. On top of that, Macs with solid state drives (SSDs) instead of hard disk drives (HDDs) also don’t need to be defragged.

With all of these factors to consider, how do you know if you should defrag a MacBook, iPad, or other Apple device? Don’t fret. This article will walk you through the following:

  1. What is defragging, and how can it help my Mac?
  2. When should I consider defragging my Mac?
  3. How to check storage.
  4. Why SSDs don't need defragging and other advantages.

Let's get started.

What is defragging, and how can it help Macs?

Hard disk drives (HDDs) store data on a spinning platter that’s divided into sectors. Over time, the data for a saved file becomes fragmented, meaning parts of the file are stored on different sectors of the disk. This creates inefficiency, as the mechanical arm accessing a file must move to multiple sectors to collect the various bits of data a computer needs to read and open it. This unsystematic storage also creates spaces between saved data on the disk that aren’t usable, reducing storage capacity.

Defragmenting basically reorders the data on the hard disk and bunches those bits together, making it faster and more efficient to access save files. Defragging also restores unusable capacity by reducing the space wasted between saved data.

In general, it’s a good idea to defrag Macs or PCs with HDDs about once a month. There can be a few reasons why a Mac could be slow, but defragging may help. But, again, not all Macs need to be defragged. Let’s get into how to identify whether a Mac is a good candidate or not.

When is it time to defrag a Mac?

Defragging Mac computers became less important with the release of Mac OS X 10.2, an operating system version from way back in 2002. Starting with that version, Macs came equipped with a new filing system that did a better job grouping of data together, reducing fragmenting and the need to reorganize the data later. Mac OS X 10.2 and later versions also perform some defragmenting functions on an automatic basis.

Macs are known for their longevity. If you’re running an older OS X version than 10.2, chances are strong that defragging a Mac disk will improve performance. If a Mac has a newer operating system, it won’t even include commands to give you the option to defrag a disk drive.

How to check storage

Checking a Mac’s performance can help you determine whether you need to defrag or upgrade. Perhaps you received a warning message that a startup disk is almost full. Perhaps you’ve noticed a Mac is performing slower and want to see whether you’ve eclipsed that 90% storage threshold. The steps for checking how much storage is available on an HDD, follow these basic steps:

  • Click on the Apple logo in the top, left-hand corner of the screen.
  • Click “About this Mac.”
  • Click “Storage.” You’ll see how much space is available on a drive as well as graphs illustrating what kinds and size of files are stored on a hard disk.

How to check whether a Mac has an HDD or SSD

As previously stated, SSDs should not be defragmented. But how do you know if a Mac has an SSD or an HDD? Here’s how to find out:

  • Pull down the Apple menu.
  • Select "About This Mac."
  • Select "More Info."
  • Click "System Report."
  • Under the "hardware" tab, select "Serial-ATA."
  • The resulting information will show the storage device's type, make and manufacturer.

Why SSDs don’t need defragging and other SSD advantages

Newer OS X versions can run into capacity problems, especially if you chew up GBs of space with video files, photos, or files created editing software or other applications that require a ton of data. If a Mac is using more than 90% of its disk capacity, the operating system will no longer run those automatic defragmenting programs. If that happens, peruse saved files and applications and delete whatever you no longer need. Start with multimedia files, like videos, that take up more storage space. Another solution is to add capacity by upgrading storage—including possibly to an SSD. There are many advantages to an SSD in addition to never needing defragging, including faster bootups, enhanced durability, automatic encryption options, and faster read/write times.


Unless a Mac runs on OS X 10.2 or earlier, defragging a Mac likely isn’t the best solution for boosting performance. In fact, later versions don’t give you the option. And, if a Mac has an SSD, you shouldn’t defrag anyway. However, if you are running out of storage space, upgrading from an HDD to an SSD is a simple way to boost speed, add capacity, and enhance security for a Mac.