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 installation process.
This guide will teach you how to create and install a clean copy of Windows 10 on a custom partition.
Create partition during installation of Windows 10
To install Windows 10 on a custom partition, use these steps:
Start your PC with a Windows 10 USB flash media.
Important: To start a device with a bootable USB flash drive, you need to 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.
Press any key to begin.
Click the Next button.
Click the Install now button.
Type the product key, or click the Skip button if you’re reinstalling Windows 10.
Check the “I accept the license terms” option.
Click the Next button.
If you skipped the product key, select the edition of Windows 10 to install.
Click the Next button.
Select the “Custom: Install Windows only (advanced)” option.
Select each partition in the hard drive to install Windows 10 and click the Delete button. (Typically, the “Drive 0” is the storage containing all the installation files.)
Warning: Deleting a partition also deletes all data within.
Select the “Drive 0 Unallocated Space” item.
Click the New button.
Specify the amount of space (in megabytes) to allocate for Windows 10 and apps. (The operating system requires at least 20GB of space, but to prevent problems with future updates and running out of space to install applications, you should be creating a partition between 60GB to 100GB in size. If you plan to install large applications, it’s a good idea to reserve even more space.)
Click the Apply button.
Click the OK button. (Alongside the custom partition, Windows 10 will also create the additional partitions automatically required to install and run the operating system.)
(Optional) Select the “Drive 0 Unallocated Space” item.
Click the New button to create additional partitions with the remaining space. (You can always perform after the installation.)
Select the “Drive 0 Partition 4 (Primary)” item from the list.
Click the Next button.
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 partition with 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:
Open Start.
Search for Disk Management, and click the top result to open the app.
Right-click the unallocated space on the drive and select the “New Simple Volume” option.
Click the Next button.
Specify the amount of space (in megabytes) for the partition in megabytes.
Click the Next button.
Use the “Assign the following driver letter” drop-down menu and select a letter to make the drive available in File Explorer.
Click the Next button.
Select the “Format this volume with the following settings” option.
Use the “File system” drop-down menu, and select the NTFS option.
In the “Allocation unit size” setting, leave the Default option.
In the “Volume label” field, type a name for the drive—for example, Data.
Check the “Perform a quick format” option.
Clear the “Enable file and folder compression” option.
Click the Next button.
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.
