If you have recently upgraded or replaced the hard drive for your MacBook or iMac, you will need to reinstall macOS onto it. This guide will show you how to install macOS High Sierra onto a blank hard drive.

Before you begin, you will need to create a bootable flash drive. This requires having access to a Mac currently running High Sierra, in order to be able to download the 7.7 GB High Sierra file in the App Store. You will so need an empty flash drive that can fit 5.4 GB.

Follow this guide to create a bootable macOS High Sierra flash drive before proceeding with the guide.



Nessuna parte richiesta.

  1. With the device powered off, disconnect any external hard drives and flash drives.
    • With the device powered off, disconnect any external hard drives and flash drives.

    • Plug in your macOS High Sierra bootable flash drive.

    • Hold down the [option] or [alt] (⌥) key on the keyboard and power on the device.

    • When you see the boot selection screen as shown, release the [option] key.

    • Use either the keyboard's arrow keys or the mouse to select "Install MacOS High Sierra." Press [enter] or click your selection with the mouse.

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  2. Your Mac will begin copying the installation files from the flash drive. This may take up to 30 minutes.
    • Your Mac will begin copying the installation files from the flash drive. This may take up to 30 minutes.

      • Depending on the speed of your flash drive, it may look like progress has frozen, but it should resume if you continue to wait.

    • When prompted, select your language and press [enter], or click the arrow button.

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  3. Diffondi allegria Fixmas
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    Diffondi allegria Fixmas
    Ottieni $12 sul tuo acquisto di $50 o più con il codice FIXMAS12
    • If you don't need to pre-configure your hard drive, skip to step 5. If you're not sure or if the drive is used, it's a good idea to pre-configure your hard drive.

    • Select "Disk Utility" from the menu and press [enter] or click the continue button.

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    • Select your hard drive from the left column in Disk Utility.

      • It is most likely the uninitialized drive.

      • If you have multiple hard drives, make sure you select the correct one as the next step will wipe the selected drive clean.

      • Click the "Erase" button at the top of the window.

      • Choose a name for your drive (you can rename it later). Leave the format as Mac OS Extended (journaled), and the scheme as GUID Partition Map.

      • Click "Erase."

      • When the process completes, click "Done."

      • Exit the Disk Utility by clicking on the red X button on the top left corner of the window.

    If, like me, you have already formatted the disk in the Windows operating system, you will probably encounter an error message when trying to select the new disk as the installation destination that warns you that the disk is not "GUID partitioned", and that you should go to erase it with the Disk Utility application.

    The trick here is to go to the DU application, select the "Show all devices" option in the top left drop-down menu and then select the root device for your disk, and not the individual partitions. That is the one that you must delete, and for that root device, the DU application will show you the option to select the “GUID Partition Map” inside the Erase button window.

    Best regards!!

    Explanation with images:

    Lucas Dasso - Replica

    • Select "Reinstall macOS" from the menu and press [enter] or click "Continue."

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    • Read through the license agreement.

    • Click "Agree" to accept the license agreement.

    • Your Mac will now install macOS High Sierra. Be patient and wait for it to complete.

    • Once the install is complete, the device will restart itself.

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High Sierra should now be freshly installed! Enjoy!

Altre 471 persone hanno completato questa guida.

Arthur Shi

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I replace Toshiba MK1231Gal dard disk based on instruction on yutube!

the problem is that when I try to install osx, I cant format the disk

I got notice input, output error, when try to make a partition or try anything with disk utility

I own MacBook air 1237

Iztok - Replica

I replace Toshiba MK1231Gal dard disk based on instruction on yutube!

the problem is that when I try to install osx, I cant format the disk

I got notice input, output error, when try to make a partition or try anything with disk utility

I own MacBook air 1237

Iztok - Replica

yes, me too...did you get it fix? please share how.

jay zee -

A small pointer for any who have the same issue. I put in an entirely new 2TB WD sata drive and then preformed a fresh install of snow leopard onto it. When I got to the section to choose which drive to install to there was no drive image.

I clicked at the top on disk utility, then picked the drive, clicked erase and erased the drive. THis actually formats it into a mac format. after this I closed disk utility and voila the drive was now visible and installation could commence.

Good luck

Sam - Replica

This guide was awesome!

Thank you!

staplesjoel - Replica

This Mac OS X Install Guide is really outdated. When using a Recovery disk to install Mavericks, OS X just told me it couldn't install Mavericks. Didn't tell me why, it just told me it couldn't do it. I did something like this:

1. Get a USB or Firewire HD enclosure. Use the iFixit HD Replacement Guide to put your new HD into your iMac and put your old HD into the enclosure.

2. Plug in the enclosure and its USB or firewire cable to your iMac.

3. Hold down the option key on your keyboard and turn on your iMac. When it boots, it should recognize your old HD in the enclosure and give you the option to boot from that drive. Select that drive. It's just like booting when the drive was still in the iMac but maybe a little slower.

4. Now go to the App Store and Download and install Mavericks. You'll need to select "Show all Disks". You may need to use Disk Utility to format or erase your new HD if it doesn't show up. Use Migration Assistant to transfer apps and data from your old HD to your new HD in the iMAC.

Wade Bick - Replica

Thanks for helping others! This install guide is specifically for Mac OS X 10.5 Leopard. We are working to make guides for installation of the more current OS's, but they haven't been completed at the current time.

Mike -

Hi, my questipn is: i have to insert the os cd before installing the new hard drive?

Miguel Yanez - Replica

You do not need to install the disk prior to installing the Hard Drive.

Mike -

I need help. I have 10.5.8 on my macbook. My hard drive is messed up so I cant erase the hard drive as the erase button is greyed out. So I am trying to format everything in my macbook and reinstall osx. But I got 10.6 only. Please advise how to erase everything on hard disk and installing clean osx on macbook? Is anything I should know?

Ahmd Faruq - Replica

Depending on your MacBook, you may be able to install Mac OS X 10.6 onto that machine. You will need to boot up from that disk prior to doing the erase of the hard drive as well.

Mike -

After installing new HDD in IMAC...power on gives a yellow screen. Is it possible to get to formatting utility from this point? I tried a command R no luck.

2nd attempt I tried inserting Snow Leopard disk, tried 'option' key at power on, tried Cmd-R, tried no key; disk goes into a cycling routine but nothing appears on screen.

Rich - Replica

I think what's Happening Here is a lot of people aren't formatting drive before hand. Old drive dies new one pop in and your good. This is not the case Mac, Kaspersky uses a tool to allow you to make a bootable disk from your usb for your Mac or your PC. Use the tool that used because there are a lot of viruses out there. That what you want to do since you don't want to rip your Mac apart is download Ubuntu ISO file learning is a bootable ISO you can use FAT32. Once you do that put it in the USB drive boot from the USB. Sorry forgot to stop you need to get rid of your vram clear option RVP or something. Next is booted off the USB having its command option r. Now you want to format Drive using Ubuntu. Yes Ubuntu free where is more powerful that are Mac OS X and it's free. Now you have to remember using a Mac which is a Linux machine and it's grub so the file extension is htls. Grub you do not format NTFS…

Kapsol -

Once you've done that you need to os. So you can pay the $20 for it which is a joke you could download it from a torrent I'd be very careful doing that or if you have a 2011 that came with it manhole command-r now the problem here is it will not allow you to connect. Therefore you need to open your router settings if you have an old router that would be best.

Kapsol -

Set that router up to connect to an open DNS so where it says DNS connection you want to use Google DNS OpenDNS Mike's DNS ect Google DNS in OpenDNS are the best. And then you have to hold command-r and it now will allow you to connect to get the file. Once that gets the file it'll start the installation process your screen will turn white let it turn white holdzkom and wipe out the vram again reboot redo it and your set. And now if you're still having problems do a hardware check I think that's holding the just hold D at start up. Keep hope alive. You guys can donate for all my time put into this BS very awesome even $0.10 a penny anything be better than nothing kapsol101@yahoo is my email and PayPal if you have problems just email me now I'm always here to help. Unless I die like Steve Jobs did cuz karma's a bch.

Kapsol -

I have a MacBook Early 2009 A1181 Model. Just ordered a SSD from Amazon, and have all of my stuff backed up on the external hard drive I use for backing up. I still have all of my installation CDs, but want to make sure of the tools I need for this. I know I take the battery out, and that metal cover in that area, but for my Mac I'm not sure if it would be the same tools since it is older than what you guys have.

Also, one quick question, can I change the processor in this? I will be switching out the ram soon, likely after tax season, but I want to get a faster processor if possible.

rtaillon1 - Replica

I replaced the original 320 GB OEM Apple/Hitachi drive in my 2007 iMac with a 3 TB Hitachi/HGST drive today using the iFixit guide. To reinstall OS X, I used an Apple USB thumb drive, which after reformatting with Disk Utility, is currently downloading Lion from Apple. I also decided to run the formatting/reinstallation before reassembling the front bezel and glass, in case my son and I did something wrong in the drive replacement. Fortunately it looks like we did everything right.

recmsoj - Replica

Thought that I would add this comment in case someone has similar situation. MBP late 2011 replaced HD with SSD (Samsung 850 EVO). The angle on the install was that my Time Machine and Old HD were encrypted. When encrypted (Time Machine and CCC clone of drive), the Recovery HD is not setup (not sure details, perhaps this is how encryption works). Either way, setting up a bootable Install USB drive (8 gig minimum for Yosemite) was necessary. Sequence was full backup (I did both Time Machine and CCC to be sure)., create bootable USB installer drive (Google it, I used the Disk Utility method). Shut Down, Reboot with Command-R, plug in USB drive, format new disk, load Yosemite from USB to new disk, then shut down, Restart with Command-R, then load Time Machine backup. The clean Yosemite install setup the Recover Partition on new drive and the files copied from Time Machine restored system to original state without messing with newly created Recovery partition. Then encrypt new drive and you are done.

Brian - Replica

Hi,I am getting ready to replace the drive in my early 2008 20" iMac. I have a Time Machine backup but do not have the OS installation disks. How can I get replicate my current drive contents to the new disk?

Jenerationnyc - Replica

Thank U, Clear I would like to test and check. :)

Sasteam Vander - Replica

please mention Customize ,that can save many GB of disk space with unwanted junk.

Andrew Waddington - Replica

How do you install 10.5 over 10.7) (which is on a 2nd partition) to downgrade to 10.5 due to having to use some software limited to 10.5?

Greg Brooker - Replica

How do you install 10.5 over 10.7 (10.7 is on a 2nd partition) to downgrade to 10.5 due to having to use some software limited to 10.5.

Greg Brooker - Replica

I don't have a Snow Leopard disc. I downloaded Snow Leopard to an external hard drive, and connected it to the mac before starting up and pressing the Option Key. All I get is a grey screen and a cursor. Is there a way to format my new 1TB hard drive using software loaded onto an external drive?

arleyrose - Replica

I don't have a Snow Leopard disc.

I downloaded it from the apple website and loaded the MacOSXUPD10.6.8.pkg onto an external hard drive and connected it to the iMac. I started it up, pressing the option key down, and all I get is a grey screen and a cursor. Is there a way to format my new 1TB internal hard drive using the software loaded onto an external drive? Kinda new to this :(

arleyrose - Replica

I just brought a PowerBook G4 it currently runs os x 10.4.11 how do I update it to 10.5 without the disco considering I can't find one anywhere!

diggadog - Replica

OK - I replaced my HD for my Mac Book Pro 15" #1211 and reloaded software and everything works... but the software upgraded to OSX Lion and again everything works... but it won't up grade to anything beyond Lion. What am I missing? Is it a hardware restriction or some other problem?

pmoretti - Replica

I replace on 2009 Imac my old HHD with a new SSD 1TbThen the screen was blank. i had to insert the Snow Leopard CD hold on option button and open the Utilitys and chose the new ssd to install the Snow Leopard.Then i did ll the updates and downlead and install all Lion,Maverik,Yosemit ,.and it works

Daniel - Replica

is anyone fix Input/Output error yet? Please help!!

jay zee - Replica

Where can I download Mac OSX Leopard 10.5?

gitico2006 - Replica

Thank you for the guide. My 2008 24 inch imac has been use as a paperweight for the past 4 years after the HD failed. I replaced it with a 27 inch imac, but I decided to have go at fixing the old one. I replaced the 320 WD HD with a WD 2 TB today. All went well until trying to reinstall the original OS (Snow Leopard) and could not get the computer to see the new HD. Your guide saved the day and now have the OS installed. Thanks again.

John Gardner - Replica

wen i am installing asking the id & password, if i give new id it not accepting. i am totally struck please help me

Sathish m - Replica

So you can't use a hard already in the Dell gx280? Or if you can does it delete all the information that you used before trying to install mac os on your Windows pc? Probably stupid but really curious? This dell has been a soldier for me but I'm not able to purchase a Mac right now and want that operating system so bad.

Ryan Ridgeway - Replica

There is no normal way to install Mac OS on normal PC, for limits of Apple. You can Google "Hackintosh" for installing Mac OS on a Windows PC.

ycwei982 -

I am trying to re-install OS X Leopard onto a Macbook A1181 and can get to the picture in Step one less the HD option. When I click on the Install Disk the drive starts then the Laptop re-boots. It never gets to step two. I can hear the HDD spinning and have checked the RAM but do not know what to check next other than try checking the HDD to make sure it is good.

khutch9999 - Replica


I printed out this guide before I replaced my SSD, however the graphics for Steps 6 to 17 did not print - the graphics for Steps 1 to 6 were fine - any ideas to solve this issue?

Best wishes,


Gary Brooker - Replica

How would i do this without a functioning optical drive

James Reynolds - Replica

Need some help. Installing High Sierra on my MacBook Pro Mid 2009 - did all the steps to put it on a brand new external drive. It is plugged into my computer, I can see the High Sierra install when it comes on and when I click it it goes to a grayish/white screen with a circle slash no symbol, like the ghostbusters, then use sits there and does nothing.

Robert Warfield Jr - Replica

It’s normal, The minimum hardware requirement for High Sierra is a MacBook Pro Mid 2010.

So, go to make a new usb drive with Sierra.

Anthony Fassler -

In step 5 of this guide would it work to choose “Restore from Time Machine Backup” instead of “Reinstall macOS”, connect my Time Machine backup via USB and restore my HD? Or do I first have to install the OS on the new empty disc and then load my backup?

Stephan Gysi - Replica

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