Mac Tutorials

How to Defrag a Mac

If you’ve ever used a Windows computer, you might have used disk defragmentation to optimize your computer’s performance. Windows OS has always included its own built-in defrag software made for this task.


But what if you’re using a Mac? macOS (previously Mac OS X) doesn’t come loaded with any sort of equivalent disk defragmenter. (However, it has Disk Utility and Apple Diagnostics to fix your Mac’s hardware).


So what should you do? Is there a way to manually run defrag on a Mac? Is it necessary to do so and is it safe? Find all the answers in our article.


Before we start:


Mac defragmentation isn’t really an issue, particularly with machines that use solid-state drives (SSDs). If you want to optimize your Apple computer, you’re better off deleting unwanted files and old cached data. Thankfully, that’s easy with MacKeeper’s Safe Cleanup tool:

  1. Download MacKeeper, run it, and select Safe Cleanup.
  2. Click Start Scan.
  3. When it’s done, select what to delete, and click Clean Junk Files.

With the junk gone from your Mac, you’ll free up disk space and have a generally more responsive system.

What is disk defragmentation?

Defragmentation is the process of reversing fragmented data on computer hard drives. When files are stored and accessed on a traditional hard drive, bits of their data can end up spread across different locations on that hard drive’s platters (spinning disks inside the drive).


When files are fragmented, accessing them takes longer. Defragging organizes files so all their data is stored together. This way, it’s easier and faster to read a file.  

How does defrag work on Mac?

Unlike Windows, macOS doesn’t have any kind of built-in defrag tool. We’ll explain why in a moment. Just know that if you do want to run a disk defrag on your Mac, you’ll need to use some kind of third-party tool.

Why is defragmentation good for a PC but not for a Mac?

When storing files on hard drives, Windows puts data wherever there is free space on the drive. If you delete files, their spaces open up. This means you can end up with lots of free spaces spread out across your hard drive, and when you store a large file, it can get divided among those free sectors.


Reading such a file takes more time because the system needs to access several sectors to read it. The head inside the drive will need to move from sector to sector, looking for all the different parts of the file. This behavior means Windows needs to be defragged from time to time.


The Mac file system works differently, preventing fragmentation from happening in the first place. Since Mac OS X 10.2 (Jaguar), Macs have had a feature called Hot File Adaptive Clustering, which stores frequently used files in a special ‘hot zone’ for quick access. As they’re moved, the system defrags them on the fly. This applies to both of Apple’s Mac file systems—Mac OS Extended (HFS) and Apple File System (APFS).


Unless you have a very old Mac, you won’t need to defrag, which is why Mac optimization software doesn't usually include defragging as a feature.

Should you defrag a Mac?

Will defragmenting a Mac or MacBook do it any good? Here’s a short answer:

 Do you have an older Mac with a traditional hard drive?Do you have a modern Mac with a solid-state drive?
Should you defrag your Mac?Not really, but you can. It won’t harm your Mac.No, and it might be harmful for your Mac.

Now, for the slightly longer answer. As well as macOS and newer versions of OS X having automatic defragmentation features, you shouldn’t try to defrag an SSD. For a start, solid-state storage technology is orders of magnitude faster than hard drives, so any potential speed benefit from defragging would be unnoticeable.


Not only that, you’ll also be shortening the life of your SSD. All SSDs have a finite number of write cycles before they start to fail. Defragging uses those cycles up.

How to find out whether you have an HDD or an SSD

An HDD (hard disk drive) is an older type of storage device equipped with a rotating disk and magnetic heads, which read and write data to the disk.


An SSD (solid-state drive) uses flash memory to store information and doesn't have a spinning disk inside. This kind of storage device was introduced in a MacBook Air in 2008 and has been increasingly used by Apple ever since. Today, all new Macs use SSDs exclusively—from the Mac mini and MacBook Pro laptop to Apple’s top-of-range Mac Pro desktop systems.  


It’s easy to check what type of drive your Mac has:

  1. Go to the Apple menu, and select About This Mac.
  2. Click More Info.
  3. In the General section, scroll down and click System Report.
  4. Go to Storage and check under File System.
Click the Apple icon in the top left of your screen, in the menu bar, then click About This Mac. This is the first step towards checking your file system.
Step 1. Select About This Mac
You'll see a panel with a short summary of key information about your Mac and macOS. Click the More Info button now to learn more.
Step 2. Click More Info
You'll be taken to the About section in System Settings. From there, scroll down to the bottom on the right-hand side and click the 'System Report' button.
Step 3. Select System Report
In the sidebar, scroll until you find Storage. Select it, then look in the right-hand pane for information about you Mac's storage, including the file system.
Step 4. Check your file system

When does a Mac need to be defragged?

In some rare situations, your Mac may benefit from defragging. If you meet these criteria, you may want to defragment the hard drive on your Mac:

  • You need to be using an HDD.
  • You frequently work with media files larger than 1GB.
  • You have less than 10% of your disk space left.

In such situations, macOS may not have enough capacity to automatically defrag your files. Based on our research, though, the built-in algorithms in macOS handle arranging files fairly well, and your Mac will only need additional defragmentation if it’s really old.


Besides, macOS doesn’t come with a program for defragmentation, and you can’t use Terminal on Mac to do it either. But if your Mac is really old and running slow, you can still defrag your hard drive by installing third-party software. Choose the one you like the most and follow the instructions provided by the developer.

Can defragmentation harm a hard disk drive?

The short answer? No. Defragmentation isn't harmful to hard drives (HDDs), and sometimes may be quite helpful and effective for slow computers, provided you perform it correctly.


Defragmentation arranges the data and makes it more accessible, and it is safe for an HDD. It won’t remove or damage your data in any way. However, while it’s particularly useful for Windows operating systems, Macs generally don’t need any kind of defragging.

Why is defragging an SSD a bad idea?

If you own a Mac with an SSD instead of an HDD, you should never defrag it. SSDs operate differently and have their own maintenance routines. And because SSDs don’t have mechanical parts, your Mac can reach each sector at roughly the same speed.


Moreover, SSDs have a limited number of read and write cycles, and defragmentation is actually a process of reading the data from one sector and writing it to another. So defragging an SSD will shorten an SSD’s lifespan and lead to its deterioration. If you’re worried, follow our guide on how to check your Mac’s SSD health.

Other ways to care for your MacBook

As a way of optimizing your Mac, defragging is almost never worthwhile. With newer Macs, it can even lead to more performance problems, because SSDs can be harmed by defrag routines.


Rather than running disk defrag on your Mac, try our six tips for Mac optimization:

  1. Regularly clean junk files from your MacBook
  2. Check and optimize your Mac storage
  3. Optimize battery charging
  4. Install software updates promptly
  5. Perform regular backups
  6. Avoid harmful software

1. Regularly clean junk files from your MacBook

The more you use your Mac, the more you can end up accumulating old cached data and other junk files. These take up space unnecessarily, which can ultimately affect your Mac’s performance. Here’s how to do it manually:

  1. Press Cmd+Space to bring up Spotlight, then type or paste in ~/Library/Caches, and select the Caches folder.
  2. Look through the Caches folder. The names of the folders in there will reveal what apps they relate to.
  3. Delete a folder to clear the cache for each app.
There are several ways to get to your Caches folder. One of the quickest methods is to use Spotlight, which you can access by pressing Cmd+Space.
Step 1. Use Spotlight to open your Caches folder
In Library > Caches, you'll see lots of folders. These contain temporary files (caches) for all the different apps installed on your Mac.
Step 2. In the Caches folder, you'll see lots of cached data
To clear the cache of an app, locate its folder in Caches, then send it to Trash. Finally, empty your Trash to delete the data from your Mac.
Step 3. If there's anything you want to remove, send it to your Trash as normal

Note from our experts: 


Manually deleting caches is time-consuming and potentially dangerous. Save time and make sure you don’t delete anything with MacKeeper’s Safe Cleanup feature:

  1. In MacKeeper, select Safe Cleanup, and click Start Scan.
  2. When the scan is done, select what to remove and click Clean Junk Files.
  3. Click Skip Trash/Empty Trash.
Open up MacKeeper, then select Safe Cleanup from the sidebar. Next, click Start Scan and wait for the tool to finish its scanning process.
Step 1. Open and run Safe Cleanup
When the scan is done, Safe Cleanup will show you a list of things you can safely remove from your Mac. Make your selection, then click Clean Junk Files.
Step 2. Select what to clean up
Finally, choose whether you want to empty your Trash at the same time or just skip it and clean only the junk files you've already selected.
Step 3. Choose to skip or empty Trash

2. Check and optimize your Mac storage

If your Mac’s hard drive gets very full, it could prevent the automatic Mac defragmentation from happening. Avoid that problem using the macOS built-in storage optimization settings:

  1. Open System Settings, and go to General > About. Scroll down and click Storage Settings.
  2. Click on the i icons to open up storage optimization tools for each file type.
  3. Use each tool to delete unneeded data on your Mac’s hard drive.
In macOS System Settings, go to the General section, then About. Finally, scroll down and click the Storage Settings button.
Step 1. Click Storage Setting
In the Storage Settings, you'll see all kinds of information about what's stored on your Mac. You can also use the tools here to optimize your disk space.
Step 2. Click the info buttons for optimization tools
macOS includes all kinds of tools for optimizing your storage space. They include a Large Files finder, which identifies some of the biggest files on your Mac.
Step 3. Use macOS's built-in tools to clear up your storage

3. Optimize battery charging

Although it won’t help with your hard disk, Optimized Battery Charging can extend the life of your MacBook battery. In macOS Big Sur or later, this feature automatically pauses your charging at 80% if you use your Mac mostly when it’s connected to mains power.


You can toggle this feature on and off at any time:

  1. Open System Settings, and select Battery. Click the i button (Show Detail) next to Battery Health.
  2. Turn off Optimized battery charging, and choose Turn Off or Turn Off Until Tomorrow. Click Done.
Optimized battery charging prevents your MacBook's battery from being at 100% all the time, which is bad fo its long-term health.
Step 1. Enter your MacBook's battery settings
You can turn off optimized battery charging in your MacBook's System Settings. If you use your Mac plugged into the mains most of the time, you should leave it on.
Step 2. Turn off Optimized Battery Charging

If your MacBook is running slow, it could be the result of a faulty battery, which can cause the CPU to slow down. Check our guide to know how to handle this issue.

4. Install software updates promptly

To avoid problems with your Mac, including potential disk fragmentation, you should always keep macOS and installed apps up to date. Follow these steps to check for macOS updates:

  1. In System Settings, check the sidebar for available updates.
  2. Click the update if you see one. Then click Update Now.
  3. Click Agree and follow the on-screen instructions.
If your Mac has any updates available, you'll be able to see them in System Settings. They'll be flagged up in the sidebar on the left.
Step 1. Check System Settings for available updates
To apply an update, click 'Software Update Available', then click the Update Now button. You'll also be able to see information about what the update is.
Step 2. Apply any updates you see
In many cases, you'll need to look at some legal information about then confirm that you agree with them, in order to install the update.
Step 3. Click Agree

Hint from our team: 


Keeping individual apps up to date is more time-consuming, particularly if you have a lot of third-party programs installed. With MacKeeper’s Update Tracker, you can update lots of apps at the same time in just a few clicks:

  1. In MacKeeper, select Update Tracker, and click Scan For Updates.
  2. Once the scan is done, look through the list, select what to update, and click Update.
  3. If any of those apps are open, click Quit All. Make sure to save your work first.
Using MacKeeper's Update Tracker you can scan your system for apps that need to be updated. Then you can update them all in one go.
Step 1. Run Update Tracker
When Update Tracker is finished scanning your Mac, look through the results, choose what to update, and click the Update button.
Step 2. Choose what to update
If any of the apps you're trying to update are currently running, you'll need to quit them first. MacKeeper's Update Tracker can do this for you.
Step 3. Quit any apps that are running

5. Perform regular backups

If you’re smart, you’ll have set up Time Machine to make regular backups. This built-in tool can make complete copies of your Mac hard drive, as well as snapshots that let you restore files that you’ve deleted or changed. If you’re going to run a defrag on your Mac, it’s a good idea to make sure your data is backed up first. You’ll need to plug in an external drive, formatted to a macOS-compatible format.


Here’s how to set up Time Machine:

  1. Go to Settings > General > Time Machine.
  2. Click Add Backup Disk.
  3. Select your external drive, and click Set Up Disk.
  4. Choose your settings, then click Done.
Go to your Mac's System Settings, then go to General > Time Machine. From there, you'll be able to set up your backup options.
Step 1. Open Time Machine settings
In the Time Machine settings, you'll be able to see any backups you've already got set up. To start a new backup, click 'Add Backup Disk'.
Step 2. Click the Add Backup Disk button
You'll need to have an external disk connected to your Mac to use Time Machine, formatted to a macOS format. Select it here.
Step 3. Choose a backup location
You can choose whether or not to encrypt your backup, in  which case you'll need to set up a password. Finalise your settings, and click Done.
Step 4. Finalize your settings

6. Avoid harmful software

Malware can do all kinds of damage to your Mac. As well as being a threat to your privacy and finances, some malicious software may write a lot of data to your Mac’s storage. If your Mac uses a hard drive, that could potentially result in the need to defragment your Mac.


As always, follow basic cybersecurity tips to avoid malware:

  • Avoid websites you don’t trust, and never click on pop-ups.
  • Don’t open email attachments from people you don’t know.
  • Don’t install software from untrusted sources or piracy sites.
  • Make sure you have antivirus with real-time protection installed.

Don’t defrag. Declutter.

There are several reasons you shouldn't bother with Mac defragmentation. Unless your Mac is very old, it’ll automatically defragment files anyway. And if your Mac is one of Apple’s newer devices, it won’t have a hard drive at all but rather an SSD, which isn’t worth defragging.


If you’re concerned about the performance of your Mac, you’re better off using MacKeeper’s Safe Cleanup to remove junk data. With practically no effort, you can find and remove unnecessary files that are clogging up your SSD or HDD, giving you a leaner, cleaner Mac. MacKeeper is also packed with other security and optimization tools that can be crucial to your system.

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