How to create custom partition during install of Windows 10

You can create and install Windows 10 on a custom partition, and here's how.

Windows 10 install in custom partition
Windows 10 install in custom partition / Image: Mauro Huculak
  • To create a partition during the installation of Windows 10, start the PC with a bootable USB, continue with the installation process, choose the “Custom: Install Windows only (advanced)” option, select and delete the correct partitions, choose the “Drive 0 Unallocated Space,” click “New,” set the storage size, click “Apply” and “OK.”

On Windows 10, you can resize a partition at any time. However, if you plan to create a dual-boot system or want to keep files separate from the installation, you can create a custom partition for Windows 10 and apps during the Windows Setup installation process.

In this guide, I will teach you how to create and install a clean copy of Windows 10 on a custom partition.

Create a partition while installing Windows 10

To install Windows 10 on a custom partition, use these steps:

  1. Start your PC with a Windows 10 USB flash media.

    Important: To start a device with a bootable USB flash drive, you must change the BIOS settings. This process usually requires pressing one of the function keys (F1, F2, F3, F10, or F12), the ESC, or the Delete key. For more accurate instructions, visit your PC manufacturer’s support website. Also, this process will delete everything on the hard drive. As a result, it’s recommended to backup any files before proceeding.
  2. Press any key to begin.

  3. Click the Next button.

  4. Click the Install now button.

    Windows 10 Install now button

  5. Confirm the product key or click the Skip button if you’re reinstalling Windows 10.

    Windows 10 setup, product key settings

  6. Check the “I accept the license terms” option.

  7. Click the Next button.

  8. Select the edition of Windows 10 to install (if applicable).

    Windows 10 setup, select edition to install

  9. Click the Next button.

  10. Select the “Custom: Install Windows only (advanced)” option.

    Windows 10 setup, custom install option

  11. Select each partition in the hard drive to install Windows 10 and click the Delete button.

    Warning: Deleting a partition also deletes all data within. Typically, the “Drive 0” storage contains all the installation files.
  12. Select the “Drive 0 Unallocated Space” item.

  13. Click the New button.

    Windows 10 setup, create custom partition

  14. Specify the amount of space (in megabytes) to allocate for Windows 10 and apps.

    Windows 10 setup, specify partition size

    Quick tip: The operating system requires at least 20GB of space, but to prevent problems with updates and running out of space, you should create a partition between 60GB and 100GB. If you plan to install large applications, it’s a good idea to reserve even more space.
  15. Click the Apply button.

  16. Click the OK button.

    Quick note: Alongside the custom partition, Windows 10 will also create the additional partitions automatically required to install and run the operating system.
  17. (Optional) Select the “Drive 0 Unallocated Space” item.

  18. Click the New button to create additional partitions with the remaining space. (You can always perform after the installation.)

  19. Select the “Drive 0 Partition 4 (Primary)” item from the list.

  20. Click the Next button.

    Select partition to install Windows 10

Once you complete the steps, the setup will install Windows 10 on your created custom partition.

After the installation, you will need to go through the out-of-box experience (OOBE) to create an account and finish configuring the installation.

Create a partition with the remaining unallocated space

If you did not use the remaining space during the installation, you can use these steps to create an additional partition to store files and other items:

  1. Open Start.

  2. Search for Disk Management, and click the top result to open the app.

  3. Right-click the unallocated space on the drive and select the “New Simple Volume” option.

    Disk Management, New Simple Volume option

  4. Click the Next button.

  5. Specify the amount of space (in megabytes) for the partition in megabytes.

    Specify partition size for a new drive

  6. Click the Next button.

  7. Select a letter to make the drive available in File Explorer using the “Assign the following driver letter” setting.

    Assign drive letter to new partition on Windows 10

  8. Click the Next button.

  9. Select the “Format this volume with the following settings” option.

  10. Choose the NTFS option from the “File system” setting.

  11. Select the Default option in the “Allocation unit size” setting.

  12. Confirm a name for the drive—for example, Data in the “Volume label” setting.

  13. Check the “Perform a quick format” option.

    New partition format settings on Windows 10

  14. Clear the “Enable file and folder compression” option.

  15. Click the Next button.

  16. Click the Finish button.

After you complete the steps, the partition should format with the settings you specified, and it should now be available for use in File Explorer.

Update January 23, 2024: This guide has been updated to ensure accuracy and reflect changes to the process.

About the author

Mauro Huculak is a Windows How-To Expert who started Pureinfotech in 2010 as an independent online publication. He has also been a Windows Central contributor for nearly a decade. Mauro has over 15 years of experience writing comprehensive guides and creating professional videos about Windows and software, including Android and Linux. Before becoming a technology writer, he was an IT administrator for seven years. In total, Mauro has over 21 years of combined experience in technology. Throughout his career, he achieved different professional certifications from Microsoft (MSCA), Cisco (CCNP), VMware (VCP), and CompTIA (A+ and Network+), and he has been recognized as a Microsoft MVP for many years. You can follow him on X (Twitter), YouTube, LinkedIn and Email him at [email protected].