How to Dual Boot Windows and Linux on the Same PC

Dual booting lets you keep Windows and Linux on the same PC and choose an operating system at startup. It also changes disk partitions and boot configuration, so a full backup is essential before you begin.

This guide uses Ubuntu as the Linux example because Ubuntu publishes current documentation for installing alongside Windows. Other distributions can differ.

1. Back up Windows first

Before resizing partitions or changing boot configuration:

back up important files to another device or cloud location;
make sure you can sign in to your Microsoft account if BitLocker/device encryption recovery keys are stored there;
create Windows recovery media if the PC is important to you.

2. Check BitLocker or Device Encryption

Ubuntu’s installer warns that it cannot safely install alongside an encrypted Windows installation when BitLocker prevents it from reading the disk layout.

If BitLocker is enabled on the Windows partition, read the current Ubuntu guidance before proceeding. You may need to decrypt the Windows volume before using the automatic Install alongside Windows option.

Keep the BitLocker recovery key even if you temporarily disable encryption.

3. Make room for Linux

You can shrink the Windows partition from Disk Management:

Right-click Start > Disk Management.
Right-click the Windows data partition you want to shrink.
Select Shrink Volume.
Leave the new space unallocated for the Linux installer.

Do not format the unallocated space in Windows unless your Linux distribution specifically instructs you to.

4. Create Linux installation media

Download the ISO from the Linux distribution’s official website and use the distribution’s recommended USB creation method.

For Ubuntu, a USB drive of 12 GB or larger is recommended by current documentation.

5. Boot the USB in UEFI mode

Restart the PC and use the manufacturer’s boot menu key to select the USB device. Modern Windows systems normally use UEFI.

Do not disable Secure Boot automatically. Current Ubuntu releases support Secure Boot on compatible hardware. Change firmware settings only when your Linux distribution’s documentation says it is necessary.

6. Use “Install alongside Windows” when offered

During Ubuntu installation, choose Install Ubuntu alongside another operating system/Windows when the installer detects the Windows installation and offers that option.

The installer can then allocate space while preserving Windows. Manual partitioning is for advanced users who understand EFI system partitions, filesystem layout, and bootloaders.

The recovered draft prescribed a fixed /dev/sda GRUB target and a swap partition equal to RAM. Those rules are not appropriate for every modern PC—NVMe drives use different device names, and current Ubuntu installations do not require that old swap-partition formula.

7. Test both operating systems

After installation:

Reboot and confirm the boot menu appears.
Start Linux and verify networking, graphics, sound, and updates.
Restart into Windows and confirm Windows still boots normally.
Re-enable encryption only after checking the relevant Windows/Ubuntu guidance and confirming your recovery keys are safe.