Before I buy a new SSD, I wanted to see if the following is possible:

I have a 500 GB HD in my MacBook Pro that is using only 240 gigs. Can I clone this to a 256 GB SSD drive? (My goal is to replace the boot spinning drive with an SSD drive.) Then use the 500 GB HD as a second drive in the SuperDrive bay.

Can I clone to the SSD if it's in a USB enclosure as well?

And what is the best cloning software?

I'm running OS X Lion, if that's useful.

6 Answers 6


You can do that, however having so little space left on the SSD after cloning might be an issue when you start running the machine.

You can use either Disk Utility (in Utilities, or better, you could start from the Snow Leopard DVD and start it from there); SuperDuper! (I've used that), or Carbon Copy Cloner. But be very careful, make sure that you don't switch the source and target (you'll lose everything) and make sure that you can boot from the SSD and that everything works before deleting the old drive. Find some tutorials (SuperDuper and Carbon Copy Cloner have them on their websites) print them and make sure that you understand each step before proceeding with the cloning.

Alternatively, if you can find or borrow another disk, you can create a Time Machine backup of the internal disk, replace it with the SSD and restore from Time Machine. It would be slower, but you'll have an extra copy (the Time Machine disk) just in case.

  • Time Machine would be easiest. So it can restore to a smaller drive?
    – Ian Vink
    Apr 16, 2012 at 18:13
  • I think so, although I've never tried that. It doesn't actually clone a disk (as in create an image or exact copy), but you could restore to a new disk as if it is restored from image. But for Time Machine you'll need a third disk to use as Time Machine disk.
    – lupincho
    Apr 16, 2012 at 18:37

Clone larger HDD drive to smaller SSD drive on Mac. Or migrate from an HDD to SSD.

The fastest and most efficient way can be done completely using standard tools in OS X.

This solution does not require any reinstall, all the way setup of user account and Mac settings, or separate programs or much more time consuming operations than direct disk to disk data transfer.

You need: 1 SSD drive and USB SATA adapter, it can be any enclosure, or SATA to USB adapter cable, or if you have thunderbolt or any faster connection this is even more preferred.

  1. Always have regular backup. Time Machine is recommended way. Do it to external HDD or Time Capsule device.
  2. Boot you Mac into Recovery mode. Reboot your Mac and immediately hold Cmd+R during POST stage (black screen).
  3. Open Disk Utility, locate your existing HDD and select primary partition on the left (mount point /, Type: Logical Partition), this can be named Macintosh HD and in First Aid click Verify Disk, to make sure you are error free before start.
  4. On the left now select primary disk it self (Type Logical Volume Group), and on the right select Partition tab, click + sign and drag primary partition (e.g. Macintosh HD) to resize to size smaller than new target SSD disk. Click Apply.
  5. Now you have to prepare new SSD drive. Connect new SSD drive to Mac if not done so yet, and select it on left in Disk Utility. Click Erase tab and chose name for new device, I recommend to name it SSD, so you can clearly see difference in next steps. This name is for temporary use only. Under format choose Mac OS X Extended (journaled) and click Erase. Note: if this disk already was initialized or used on other system like Windows, please delete all existing partitions before this step and start like new! This is important to have new system bootable.
  6. Poweroff and physically swap disks. Do not erase or start using old disk until everything is finished. Do not connect original disk until you are done.
  7. Perform actual data cloning. Boot you Mac into Recovery mode again (Cmd+R). Select Original Primary partition on the left (Macintosh HD) and on the right select Restore tab. Drag SSD prepared partition to Destination field (you called it SSD). Click Restore and wait so many hours, how many you have to physically copy your data from one drive to another.
  8. Reboot to Recovery mode again and choose Boot from main partition in new SSD. Click the Apple menu on the bar at the top of screen and select Startup Disk to access the Choose Startup Disk tool. The boot option will be named exactly the same as was in original hard drive, thus just select it and system will reboot into this his. Note: this step is necessary to avoid boot wait, because Mac cannot find original disk anymore, and starts into SSD only after about 30 seconds as recovery boot sequence.
  9. Reboot and system will boot fast into old Mac OS X system. Now you are done :)

Note: if your system waits about half a minute before booting when only a new disk is left on the system, then press Alt/option key during startup and just select Mac OS X system. This will reset the default OS and will clear boot wait for old device.

2020 macOS Catalina, Big Sur APFS update: If you are on APFS already, this task becomes even more trivial.

  1. Just do all steps except repartitioning and shrinking original drive.
  2. Also format new SSD drive with APFS.

If you have amount of data in original APFS Volume which fits your new hard drive, there is nothing to stop you, just recover your new drive APFS Volume with old drive Macintosh HD as a source.

Checked and confirmed its working when I was migrating old SSD to larger SSD drive, also HDD or SSD drive to NVME drive.

  • My system with 80GB of data was done in 1.5 hour. Jul 25, 2015 at 22:10
  • 2
    You can skip step 6 and do it later. Clone and test before physically switching drivers. You can turn the computer on holding option to choose to boot from the USB drive.
    – Roberto
    Apr 14, 2016 at 22:54
  • I recommend not to skip this step, it is good test if new system is bootable, else you are wasting time used for restore, and will need to redo if this step failed. Jun 8, 2016 at 12:36
  • You don't need to physically swap, you can still do the test by turning the computer on holding option to choose to boot from the USB drive.
    – Roberto
    Jun 8, 2016 at 19:07
  • Yes, this should be fine :) I just do no trust OS running over potentially not secure connection if I can avoid it. For copying data it's acceptable. Also boot speed is affected, especially on older USB. Jun 8, 2016 at 19:14

I did this just today and wanted to share my experience:

  1. I connected the SSD via a USB connection.

  2. The Disk Utility in my 2012 MacBook Pro was not able to clone to a smaller SSD. Also it was unable to partition the current HDD to a size smaller than the SSD, like Arunas Bartisius said in another answer.

    So I got the Disk Utility to just erase the SSD and format as Mac OS Extended (Journaled) (aka Journaled HFS+).

  3. Then I installed the Carbon Copy Cloner on the system and cloned the HDD to the SSD (it had no issues since the size of data was smaller than the SSD).

  4. Then I made sure that I could boot from the SSD by restarting my Mac, pressing and holding the Option key and selecting the SSD, as explained here: https://support.apple.com/guide/mac-help/change-your-mac-startup-disk-mchlp1034/mac

  5. Then I opened my MacBook Pro, swapped the HDD with the SSD.

  6. Booted into the SSD. Then I also finally updated to Catalina.


What is the useable disk space of your 256 GB SSD when it is formatted for Mac, but empty? I'll bet it's quite a bit less than 256 GB.

It is a general rule of thumb that hard drives do not work efficiently unless at least 15% of the volume of the drive (as formatted for your OS) is empty space. This is necessary for file defragmentation, a maintenance operation which Mac OS X performs automatically in the background.

So you should not put more than about 217 GB of data on a hard drive that has 256 GB of capacity when it is formatted but empty. If you actually have a full 256 GB to use, at least 38 GB should be left empty. If you do fill up more space than 217 GB, your computer will work, but the performance of the computer will become slower over time due to data fragmentation.


I'd clean off at least 20GB from the hard drive. Then install a clean OS to the SSD and use migration assistant to move the rest of the drive over to SSD.

I found that after a few years, the Mac just slowed down. Installing a fresh OS and then migrating apps and files improved performance quite a bit. Why move clutter along with the files you want?


You can do a couple of things if you intend to use an SSD in addition to your regular drive.

Firstly, using Disk Utility is likely to be the easiest way to clone it, so long as you are sure that it will fit. Open Disk Utility, select your existing disk, and click the "restore" button in the top right. You will have something like the following screenshot, although in my instance I do not have any other disks.

enter image description here

In your own window, you will see your SSD disk in the left hand column. Drag it's name into the destination field. This will create a copy of the source disk, onto the destination disk. You may need to partition your SSD first - ensure it uses the same GUID partition scheme and options as your existing drive.

Next, prove you can boot from it. Hold the Option key down, and select the SSD to boot from. It should be identical, but way faster.

Now, you can choose how to take advantage of it, and your other disk. As you are already nearly full on your boot drive, you need to clear some stuff off it. A good choice for things that don't necessarily require speed are your iTunes library and iPhoto library, as well as any iMovie files. These are most people large file collections, and there isn't usually much requirement to have them accessed lightening fast.

Moving such data and folders around is one way to clear up a chunk of space to leave your SSD room to "breathe" without worrying about filling it, but it's a manual process that can be prone to error, as well as confusing for backups etc.

Another thing you can try is moving your entire home folder. Luckily, you don't even have to move it to test this option. Go into preferences, and locate your user. Right click on your name on the left column, and click advanced. You will see an option to store your home folder elsewhere. Click choose, and point it at your old disk. It will now boot from your SSD, but use the old drive for your home folder. This effectively moves all your data, but none of your apps off the SSD, which is a simple and efficient way to get a good balance between speed and capacity requirements. If you have large apps that don't need speed, you can move them into your home folders app folders to get them off the SSD too.

enter image description here

Once you have done this, and proved that it all works fine, you have some cleanup to do. You can either just wipe the old disk, then re-copy and delete (move, effectively) your home folder back into it, of you can manually just remove the hold folder on your SSD, and all the OS folders on the original disk expect your home folder.

There are millions of ways to skin this particular cat, this is just one (albeit the simplest one), and its what I intend to do as soon as my optibay arrives :)

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