How to boot a Mac from USB media. Getting your Mac to load from a USB drive is fairly straightforward. Insert the USB boot media into an open USB slot. Press the Power button to turn on your Mac (or Restart your Mac if it’s already on). When you hear the startup chime, press and hold the Option key. Holding that key gives you access to OS X. Otherwise, call a friend who also owns a Mac and ask nicely to use theirs to make the bootable USB stick. In the Mac App Store, download the operating system installer. To quit the installer if it tries opening automatically, hit the “ESC” key on your keyboard. How to Boot Mac from USB Media. After creating a bootable USB drive, the user simply needs to plug the created drive into the open port on the Mac. Here are the steps to boot Mac from the USB flash drive: Power on the system. Press and hold the Option (Alt) key on the keyboard when the computer starts.

What you need to install Windows 10 on Mac

• MacBook introduced in 2015 or later
• MacBook Air introduced in 2012 or later
• MacBook Pro introduced in 2012 or later
• Mac mini introduced in 2012 or later
  

• iMac introduced in 2012 or later¹
• iMac Pro (all models)
• Mac Pro introduced in 2013 or later
  

The latest macOS updates, which can include updates to Boot Camp Assistant. You will use Boot Camp Assistant to install Windows 10.

64GB or more free storage space on your Mac startup disk:

• Your Mac can have as little as 64GB of free storage space, but at least 128GB of free storage space provides the best experience. Automatic Windows updates require that much space or more.
• If you have an iMac Pro or Mac Pro with 128GB of memory (RAM) or more, your startup disk needs at least as much free storage space as your Mac has memory.²

An external USB flash drive with a storage capacity of 16GB or more, unless you're using a Mac that doesn't need a flash drive to install Windows.

A 64-bit version of Windows 10 Home or Windows 10 Pro on a disk image (ISO) or other installation media. If installing Windows on your Mac for the first time, this must be a full version of Windows, not an upgrade.

• If your copy of Windows came on a USB flash drive, or you have a Windows product key and no installation disc, download a Windows 10 disk image from Microsoft.
• If your copy of Windows came on a DVD, you might need to create a disk image of that DVD.
  

How to install Windows 10 on Mac

To install Windows, use Boot Camp Assistant, which is included with your Mac.

1. Check your Secure Boot setting

Learn how to check your Secure Boot setting. The default Secure Boot setting is Full Security. If you changed it to No Security, change it back to Full Security before installing Windows. After installing Windows, you can use any Secure Boot setting without affecting your ability to start up from Windows.

2. Use Boot Camp Assistant to create a Windows partition

Open Boot Camp Assistant, which is in the Utilities folder of your Applications folder. Follow the onscreen instructions.

• If you're asked to insert a USB drive, plug your USB flash drive into your Mac. Boot Camp Assistant will use it to create a bootable USB drive for Windows installation.
• When Boot Camp Assistant asks you to set the size of the Windows partition, remember the minimum storage-space requirements in the previous section. Set a partition size that meets your needs, because you can't change its size later.

3. Format the Windows (BOOTCAMP) partition

When Boot Camp Assistant finishes, your Mac restarts to the Windows installer. If the installer asks where to install Windows, select the BOOTCAMP partition and click Format. In most cases, the installer selects and formats the BOOTCAMP partition automatically.

4. Install Windows

Unplug any external devices that aren't necessary during installation. Then click Next and follow the onscreen instructions to begin installing Windows.

5. Use the Boot Camp installer in Windows

After Windows installation completes, your Mac starts up in Windows and opens a ”Welcome to the Boot Camp installer” window. Follow the onscreen instructions to install Boot Camp and Windows support software (drivers). You will be asked to restart when done.

• If the Boot Camp installer never opens, open the Boot Camp installer manually and use it to complete Boot Camp installation.
• If you have an external display connected to a Thunderbolt 3 port on your Mac, the display will be blank (black, gray, or blue) for up to 2 minutes during installation.

How to switch between Windows and macOS

Restart, then press and hold the Option (or Alt) ⌥ key during startup to switch between Windows and macOS.

Learn more

If you have one of these Intel-based Mac models using OS X El Capitan or later, you don't need a USB flash drive to install Windows:

• MacBook introduced in 2015 or later
• MacBook Air introduced in 2017 or later³
• MacBook Pro introduced in 2015 or later³

• iMac introduced in 2015 or later
• iMac Pro (all models)
• Mac Pro introduced in late 2013 or later
  

To remove Windows from your Mac, use Boot Camp Assistant, not any other utility.

For more information about using Windows on your Mac, open Boot Camp Assistant and click the Open Boot Camp Help button.

1. 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.

2. For example, if your Mac has 128GB of memory, its startup disk must have at least 128GB of storage space available for Windows. To see how much memory your Mac has, choose Apple menu  > About This Mac. To see how much storage space is available, click the Storage tab in the same window.

3. These Mac models were offered with 128GB hard drives as an option. Apple recommends 256GB or larger hard drives so that you can create a Boot Camp partition of at least 128GB.

Each operating system could crash at one time or another. While it's safe to say that macOS is more stable than Windows, it can still be affected by issues that prevent your computer from booting up. In such cases, you might need to boot your Mac from a USB flash drive to fix the problem. This article shows you two ways to boot Mac from external USB stick, as well as some troubleshooting tips in case Mac won't boot from the target USB.

Boot Mac from USB Option l: Startup Manager

If your Mac won't boot up normally, you can set it to boot from a different drive, such as a USB stick containing macOS installation files in bootable format. The drive will have to contain a version of the OS that is compatible with the Mac. As long as you have the bootable installation USB, you can start your Mac from the USB by accessing the Startup Manager. Here are the steps to be followed:

Step 1: Insert the bootable USB into Mac and power it on.

Step 2: As soon as the startup process begins, hold down the Option (alt) key and keep it depressed until you see the Startup Manager on your screen. If there is a firmware password on your Mac, hold down the Option key until you're asked to enter that password.

Step 3: You will now see the various startup disk options, and your USB will be listed there. If you click on the Up arrow right below the icon for the USB, the computer will only startup once using this disk. If you press and hold down the Control key while making your selection, it will be saved, and your computer will boot from the USB every time, as long as it is left in the computer.

At this point, you can also use the Mac installation disk to boot your Mac from. It will appear as EFI Boot, and it works on all computers running macOS 10.9 or higher.

Boot Mac from USB Option 2: macOS Recovery Mode

As an alternative, you can start your Mac in Recovery Mode. This will allow the system to automatically detect and repair directory issues. Recovery Mode will only allow required kernel extensions to load, preventing login items and startup items to load automatically. It can also help you isolate the issue depending on whether or not the issue goes away in Recovery Mode. If the issues you have during normal startup don't show up in Recovery Mode, they are most likely fixed. That means you can reboot normally and your system should be back to normal.

Step 1: Start your Mac and hold down the Shift key. You will see the Apple logo on your screen.

Step 2: When you see the login screen, you can release the Shift key and login to your Mac.

Mac Won't Boot With Usb Plugged In

Step 3: To check whether your Mac has booted into Recovery Mode, click on the Apple logo on the top left and then on About this Mac. In the window that opens, click on System Report… You should be able to see this:

How to Fix Mac Won't Boot from USB Drive

Sometimes Mac won't boot from USB as expected. If you are unable to select a different startup disk, it's possible that your disk is not showing up in Startup Manager. If you try Method 1 above but don't see your USB drive listed there, it could mean one of the following problems:

Compatibility: It is possible that the version of macOS or Mac OS X that you have on the USB drive is not compatible with the hardware. That means you won't be able to see it in the Startup Manager so, of course, you won't be able to boot from it. In such cases, you may need to burn a compatible macOS version on USB drive in order to be able to boot Mac from it.

Mac Boot With Usb Dongle

Startup Security Utility: In certain cases where your Mac has the Apple T2 Security Chip (2018 and later devices), it may be your Startup Security Utility settings that are preventing you from booting from USB. In this situation, restart your Mac and hold down the Command + R keys when you see the Apple logo. This will put your Mac into Recovery mode. In macOS Utilities, go to Utilities >Startup Security Utility and sign in as admin. Under External Boot, select the second option - Allow Booting from External Media.

Option ROM Firmware: Another known issue is that Option ROM firmware will not load in Startup Manager until you press certain keys manually. To do this, use Method 1 to access Startup Manager. Once you are there, press Option-Shift-Command-Period. You should now be able to see the USB drive. This is not exactly a problem as much as a feature. If the USB contains Option ROM firmware, you will need to press those keys everytime to boot from your pen drive.

Mac Boot With Usb

These two methods and the troubleshooting tips should allow you to boot from USB or in Recovery Mode so you can then isolate the problem that's preventing your Mac from booting up normally.