1. Dual Boot Macos Catalina And Windows 10
  2. Mac Os X Dual Boot Windows 10 Instructions

For more information about using Windows on your Mac, open Boot Camp Assistant and click the Open Boot Camp Help button. If you're using an iMac (Retina 5K, 27-inch, Late 2014) or iMac (27-inch, Late 2013) or iMac (27-inch, Late 2012) with a 3TB hard drive and macOS Mojave or later, learn about an alert you might see during installation. Running Mac OS X on a Hackintosh is great, but most people still need to use Windows every now and them. That's where dual-booting comes in. Dual-booting is the process of installing both Mac OS X and Windows on your computer, so that you can choose between the two when your Hackintosh starts. Step 2: Open the Mac OS X 10.10 Installer File. If you're not using a bootable install USB drive of El Capitan, just head to your Applications folder and double-click on the 'Install OS X El Capitan' file. If you are using the bootable drive, restart your computer while holding the Option (Alt) key. Wait until the Startup Manager pops up, then.

On a Mac with Apple silicon

Turn on your Mac with Apple silicon and continue to press and hold the power button until you see the startup options window. From there you can start up from a different disk, start up in safe mode, use macOS Recovery, and more. Learn more about these options, including macOS Recovery.

On an Intel-based Mac

To use any of these key combinations, press and hold the keys immediately after pressing the power button to turn on your Mac, or after your Mac begins to restart. Keep holding until the described behavior occurs.

  • Command (⌘)-R: Start up from the built-in macOS Recovery system. Or use Option-Command-R or Shift-Option-Command-R to start up from macOS Recovery over the internet. macOS Recovery installs different versions of macOS, depending on the key combination you use. If your Mac is using a firmware password, you're prompted to enter the password.
  • Option (⌥) or Alt: Start up to Startup Manager, which allows you to choose other available startup disks or volumes. If your Mac is using a firmware password, you're prompted to enter the password.
  • Option-Command-P-R:Reset NVRAM or PRAM. If your Mac is using a firmware password, it ignores this key combination or starts up from macOS Recovery.
  • Shift (⇧): Start up in safe mode. Disabled when using a firmware password.
  • D: Start up to the Apple Diagnostics utility. Or use Option-Dto start up to this utility over the internet. Disabled when using a firmware password.
  • N: Start up from a NetBoot server, if your Mac supports network startup volumes. To use the default boot image on the server, press and hold Option-N instead. Disabled when using a firmware password.
  • Command-S: Start up in single-user mode. Disabled in macOS Mojave or later, or when using a firmware password.
  • T: Start up in target disk mode. Disabled when using a firmware password.
  • Command-V: Start up in verbose mode. Disabled when using a firmware password.
  • Eject (⏏) or F12 or mouse button or trackpad button: Eject removable media, such as an optical disc. Disabled when using a firmware password.

If a key combination doesn't work at startup, one of these solutions might help:

  • Press and hold all keys in the combination together, not one at a time.
  • Shut down your Mac. Then press the power button to turn on your Mac. Then press and hold the keys as your Mac starts up. You might need to wait a few seconds before pressing the keys, to give your Mac more time to recognize the keyboard as it starts up. Some keyboards have a light that flashes briefly at startup, indicating that the keyboard is recognized and ready for use.
  • If you're using a wireless keyboard, plug it into your Mac, if possible. Or use your built-in keyboard or a wired keyboard. If you're using a keyboard made for a PC, such as a keyboard with a Windows logo, try a keyboard made for Mac.
  • If you're using Boot Camp to start up from Microsoft Windows, set Startup Disk preferences to start up from macOS instead. Then shut down or restart and try again.

NOTE: This article was first published in 2013. While accurate for earlier operating systems, here’s a more recent version that also includes a note on APFS.

Dual-boot systems are a way of configuring the boot drive so that you have the option to start-up your computer (“boot”) into different operating systems. The most common reason to do this is to have both Mac OS X and Windows available on the same system.

NOTE: While dual-boot systems allow you to choose which operating system you will run, you can’t switch between operating systems without restarting your computer.

However, for me, a big benefit of creating a dual-boot system is that I can have two different Mac OS X systems, with two different versions of Final Cut Pro X, installed. Because all of my media and projects are stored on an external drive, dual-booting allows me to select which version of Final Cut Pro X I want to use for an edit.

NOTE: Actually, you can create any number of different boot disks, to run whatever software you want. Though we use the term “dual-boot,” in point of fact you are only limited by the amount of free space on your boot disk.


Before we create a new partition, we need to figure out how big it needs to be. There are three components:

  • The Operating System.
  • Applications
  • Home Directory

Most Mac operating systems take 20 GB or less to store. So, let’s estimate the OS at 25 GB, to be safe.

Open your boot disk, select the Applications folder and choose File > Get Info. The total storage space required for all your applications is listed in the top right corner. For this system, applications take 15 GB. Again, let’s round this up to 20 GB.

Finally, open the boot disk, twirl down Users and select your Home directory. (It has an icon of a house.)

Again, choose File > Get Info and write down the size. In this example, I’m using 3 GB for all my Home directory files. Again, we’ll round up to, say, 10 GB.

The size partition you need to create is the sum of these three folders: 25 + 20 + 10, or 50 GB. Your numbers will vary, but this is how you calculate the partition size you need.


As shipped by Apple, your boot disk has a single partition. (You can think of hard disk partitions as similar to rooms in a house. Right now, your “house” stores all your files in a single room filled with file cabinets.)

Partitioning allows us to create multiple rooms. The only problem is that all these different rooms must fit into the space of the original house. So, partitioning allows you to create multiple rooms, but it doesn’t expand the total storage space available to you.

Dual Boot Macos Catalina And Windows 10

NOTE: In the past, we would partition drives to organize our files. This is no longer a good idea, because there’s a performance hit in moving between different partitions. While partitioning the boot drive still makes sense, partitioning for data storage does not.

To create a partition, open Utilities > Disk Utility.

Select the text ABOVE the words “Macintosh HD.” This is because “Macintosh HD” is already a partition. You can’t partition a partition, you can only partition the hard disk that contains the partition.

NOTE: The name of your hard disk – which will probably be a gibberish of letters and numbers – will vary. The key is to select the drive that contains the Macintosh HD partition.

Once the hard disk is selected, click the Partition button at the top center of Disk Utility. If Partition doesn’t appear, you’ve selected the wrong thing in the left-hand panel.

To create a new partition, click the Plus key at the bottom left of the Partition Layout.

Click inside the new partition to select it.

In Partition Information, give your new partition a name. In this example, I called my new partition, “New Boot Disk.” (You can name the partition anything you want, using any combination of letters, numbers and spaces.

Leave Format set to “Mac OS Extended (Journaled).”

And change the size to the size we calculated at the beginning of this article. In this example, I’m using 50 GB; however, your actual number may be different.

Double-check all your entries, then click Apply to create the new partition.

You’ll get a warning message, read it, then click Partition.

After a few seconds, a new hard disk appears on your desktop. Macintosh HD is your original partition, and New Boot Disk is your new boot disk.


At this point, you need to install the new operating system on New Boot Disk, along with any applications you want to use.

When you boot into the New Boot Disk you will NOT have access to anything stored on your current boot disk. It won’t be erased, just unavailable. This includes email and everything in your Home directory.

When installation is complete, you are ready to reboot into the new partition.


Restart your system while pressing the Option key.

After a few seconds a screen appears allowing you to choose which hard disk you want to boot into. Select your new boot drive and click OK.

After a few more seconds, your computer is ready to go – and launched into the new partition.


Removing a partition will erase all the data that is stored on it; so be SURE!!! you have moved all essential data to another drive. (Removing a partition will not affect any other partition on the same, or any other, hard drive.

Go back to Disk Utility.

Select the Partition you want to remove and click the minus button in the lower left.

A warning message appears asking you to confirm your choice. Read the message, then click OK.

Mac Os X Dual Boot Windows 10 Instructions

The partition is removed, but the space it occupied is not reclaimed by the original partition.

To get the space back, drag the thumb in the lower right corner all the way down to fill the gap.

Then, click the Apply button to apply your changes.


Dual-boot systems are not for everyone. But, when you need to alternate between different operating systems, or different system configurations, a dual-boot system can make that easy.

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