Installing Linux alongside Microsoft Windows (same Hard Drive)

Dual Boot Guide • Linux + Windows (Same Drive)

Installing Linux alongside Microsoft Windows (Same Hard Drive)

This guide shows the most common dual-boot setup: keep Windows, shrink the Windows partition to create free space, then install Linux using the installer option “Install alongside Windows Boot Manager”.

* Want Windows to boot by default instead of Linux? It’s a quick easy tweak.
What you’ll see after install
Dual-Boot with Linux Ubuntu
Ubuntu + Windows boot manager
Dual-Boot with Linux Mint
Mint GRUB menu
Important
Back up important files before changing partitions. Partition changes are normally safe, but mistakes and power loss can cause data loss.

Recommended USB products for dual-boot

If you’re setting up dual-boot, these are the most common choices:

Linux Mint Cinnamon Bootable USB

Linux Mint Cinnamon Bootable USB

Very beginner-friendly and a great choice for dual-boot on most PCs.

View Linux Mint USB
Linux Ubuntu Bootable USB

Linux Ubuntu Bootable USB

Popular and widely supported — great for modern hardware.

View Ubuntu USB
Computer IT Repair Bootable USB

Computer IT Repair Bootable USB

Helpful “just in case” tool for recovery/diagnostics if something doesn’t boot.

View Repair USB

Step 1: Prepare Windows (create free space)

You need unallocated space on the drive for Linux. The easiest method is to shrink the Windows (C:) partition using Disk Management.

A) Open Disk Management

  1. Log in to Windows with an administrative account.
  2. Right-click Start → open Command Prompt (Admin) (or Windows Terminal Admin).
  3. Type diskmgmt.msc and press Enter to open Disk Management.
Open disk management

B) Shrink the Windows partition

  1. Right-click C: and choose Shrink Volume.
Shrink volume
  1. Enter how much space to shrink (in MB). Use at least 20000MB (25,000MB preferred) depending on your disk size.
  2. Click Shrink.
Enter shrink size

When finished, you’ll see Unallocated space. Leave it unallocated (do not format it). Reboot when ready to install Linux.

Unallocated space shown

Advanced: diskpart method (use with caution)

Warning: The clean command will wipe the selected disk. Only use this if you are intentionally preparing a disk and you’re 100% sure it’s the correct disk.

Alternatively, you can prepare a specific drive using diskpart:

CMD (Run as administrator)
diskpart
list disk
select disk #
clean
create partition primary
format fs=fat32 quick

Step 2: Install Linux (alongside Windows Boot Manager)

  1. Boot your PC from the Linux USB (Ubuntu/Mint/etc.).
  2. Click the desktop installer shortcut (example: Install Ubuntu).
  3. When you reach Installation type, choose:
    “Install [Linux] alongside Windows Boot Manager”.
  4. Continue the wizard and complete installation.
  5. Reboot — you should now see a boot menu to choose Windows or Linux.
Install alongside Windows Boot Manager option
Tip: If the installer does not show the “alongside” option, do not guess. It usually means the disk layout is unusual, Secure Boot/BitLocker restrictions are involved, or the free space wasn’t created correctly. Consider using the repair tools above or contact us for help.

Common dual-boot issues

Dual-boot is usually smooth, but the items below are the most common reasons people get stuck.

✅ 1) “Install alongside Windows Boot Manager” option is missing
This typically happens if Windows was not shrunk correctly, the installer can’t detect the Windows boot manager, or disk layout is unusual.

Try:
  • Boot Windows and confirm you see Unallocated space (not a new formatted partition).
  • Fully shut down Windows (not “Restart”), then boot the Linux USB again.
  • If you use BitLocker/Device Encryption, see item #3 below.
  • If it still doesn’t appear, do not guess manual partitioning unless you’re experienced — contact us.
⚠️ 2) Boots straight into Windows (no boot menu)
Many PCs will default to “Windows Boot Manager” after an update or BIOS/UEFI change.

Try:
  • Use the Boot Menu key at startup (often F12 / Esc) and select the Linux/GRUB entry.
  • Enter BIOS/UEFI and move the Linux boot entry / “ubuntu” above Windows Boot Manager.
  • If you simply prefer Windows by default, use this quick guide: set default boot OS.
🔐 3) BitLocker / Device Encryption recovery screen appears
If Windows drive encryption is enabled, changing UEFI settings or boot entries can trigger a recovery prompt.

Before making major UEFI changes:
  • Windows Pro/Enterprise (BitLocker): Control Panel → System and Security → BitLocker Drive Encryption → Suspend protection (resume later).
  • Windows Home (Device encryption): Settings → Privacy & Security → Device encryption (if present).
  • If asked for a recovery key, it may be saved in the user’s Microsoft account.
🛡️ 4) Secure Boot blocks Linux from booting
Some systems enforce Secure Boot policies that can block certain bootloaders/tools.

Try:
  • Temporarily disable Secure Boot in BIOS/UEFI (then re-enable later if desired).
  • If Windows is encrypted, suspend BitLocker first (see #3) to avoid recovery prompts.
⚡ 5) Windows “Fast Startup” causes weird boot behavior
Fast Startup can leave the Windows partition in a “hibernated” state, which can cause Linux to refuse mounting it safely.

Try:
  • Do a full shutdown (not restart) before booting into Linux.
  • If needed, disable Fast Startup in Windows Power Options (advanced users).
🧰 6) Something went wrong — how to recover
If the PC won’t boot as expected, don’t panic — most issues are fixable.