How to Dual-Boot Windows and OS X on a Mac

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Mac vs. Windows. Windows vs. Mac. Why choose when you can get the best of both worlds by dual-booting? Here's how to install Windows on your Mac using Boot Camp so you can jump back and forth between the two operating systems on the same computer.

What You'll Need

Before you start, make sure you have enough space on your hard drive for both Windows and Mac. We recommend at least 30GB for each, but the more space you have, the better. You'll also need a USB flash drive (4GB or larger) and a Windows 10 ISO disk image, which you can download here from Microsoft, and a valid Windows 10 license. Finally, make sure your Mac model can support Windows 10 in Boot Camp--check this list to find out.

Install Windows 10 on Your Mac

In the steps below, we'll use Boot Camp Assistant to create a bootable USB drive and install Windows 10 on a new partition. Then you'll be able to choose which OS you want to use whenever you start the Mac up.

1. Download the Windows 10 ISO disk image from Microsoft using this link. Choose the 64-bit version of Windows. Also, some people, including myself, have gotten an error message if the ISO image is saved to your default Downloads folder, so save the ISO image to your Documents folder or somewhere else to avoid problems.

2. Open Boot Camp Assistant. You'll find this in the Utilities folder or you can hit CMD + Spacebar to search for "Boot Camp Assistant."

bootcampassistant3. Click Continue at the Introduction screen.

bootcamp continue

4. Click Continue again at the Select Tasks screen.

bootcamp continue25. Choose the Windows ISO image and select the destination USB drive. Note that the USB drive will be reformatted, so make sure you have a copy of any of the files on it somewhere else before proceeding.

bootcamp usb

6. Click Continue and then Continue again. Your Mac will format the USB drive and create the Windows installation media.

7. Click Install to accept the partition size for each OS. By default, Windows will have a 32GB partition, but you could also click the Divide Equally button to divide your Mac's hard drive space equally between OS X and Windows.

bootcamp partition7. Follow the prompts to finish installing Windows. The Mac will need to restart to complete the process and will automatically boot into Windows 10 when it's done.

Set the Default Startup OS or Toggle Between OS X and Windows

Once you have Windows installed, you can set the default OS that will start each time you boot your Mac. To do this, head to the Startup Disk preference setting in Settings.

Every time the Mac starts, you can also toggle between OS X and Windows by holding down the Option (Alt) key immediately upon startup.

Add a comment
  • Wen123 Says:

    I started Boot Camp and run until partition. Since I only had 60GB free space (not including purgeable), it allocated 43GB to Windows. I worried that it may not be enough so hit 'Go Back' and did a few things to free up more space. When I went back to Boot Camp, it could not create boot disk on the USB. It turned out that my USB now is read only. Tried to Erase USB inside Disk Utility and tried other things like Rufus on a PC, still cannot write/Erase/Format USB. Anyone has a solution? Thanks.

  • lewis123 Says:

    its finished now!! v

  • lewis123 Says:

    How long does step 5 usually take?
    Been waiting for over an hour?

  • David England Says:

    You mention "Windows 10 ISO disk image". I have a purchased copy of Windows 10. Is the the same as the disk image that you are referring to, and can I use my CD disk instead? Thank you.

  • Francis Likongwe Says:

    I need help ASAP Please. I successfully installed windows 7 on my mac and now i cant get back to OS X. I got everything there

  • Carter ABle Says:

    I need help ASAP Please. I successfully installed windows 10 on my mac and now i cant get back to OS X. I got everything there

  • Chris Says:

    After my Mac restarts it is still in OS X, and the option for windows is not there when i go to start up disk preferences, yet up until then everything seems fine, any ideas?

  • Alexander Says:

    Thanks for the helpful instructions!

    You may not need the USB flash drive for this process. I just completed installing Windows 10 Pro to a brand new Macbook Pro (Intel i5 2.7 GHz, 8GB RAM, 256 GB SSD) and Bootcamp never prompted me to use a USB drive. I never saw the screen shown in Step 5 of these instructions.

  • Arpit Parekh Says:

    I want to dual boot Mac on Windows ? Can you provide any assistance.

  • Dani boy Says:

    Thank you for this very helpful tutorial!!

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