Until recently, if you wanted to try Omarchy you had to hand over an entire drive to it. That was the single biggest reason people bookmarked the project and never actually installed it. Omarchy 4 fixes that. You can now dual boot Omarchy with Windows 11 on the same drive, using a new free space install option that drops Omarchy into unallocated space without touching your existing Windows partition.
This guide walks through the whole process — shrinking your Windows partition, creating the bootable USB, configuring the BIOS, running the installer, and finally adding Windows back into the Limine boot menu so you can pick your operating system at every startup.
It’s one of the safest ways to set up a dual boot, because you never manually delete or resize anything Windows depends on. That said, back up anything important to the cloud or an external drive before you start. Partitioning is safe until the one time it isn’t.
What You’ll Need Before Starting
- Windows 10 or Windows 11 already installed on your PC or laptop
- A 16 GB or larger USB drive to flash the Omarchy ISO (the ISO is just under 6 GB)
- At least 50 GB of free space to carve out of your existing drive — 40 GB is the bare minimum, but you’ll regret it quickly
- A UEFI system with Secure Boot that you’re able to disable in the BIOS
- 20–30 minutes, most of which is waiting on the USB flash
Step 1: Create a Windows System Restore Point
Before you change anything, take a snapshot of your current Windows state. Open the Start menu, search for “Create a restore point”, and open it. Select your system drive, click Create, and give the restore point a name you’ll recognise later.
This takes about a minute and gives you a rollback path if anything goes sideways with the bootloader. It isn’t a substitute for a real backup of your files, but it’s the cheapest insurance you’ll ever buy.
Step 2: Disable BitLocker Encryption
This step is not optional, and skipping it is the most common reason free space installs fail.
BitLocker encrypts the entire drive, not just the Windows partition, so the Omarchy installer can’t safely write to unallocated space on an encrypted disk. If you’re on Windows 11 Pro, go to Settings → Privacy & Security → Device encryption and toggle BitLocker off. Decryption can take a while on a large drive, so start it and go make coffee.
If you’re on Windows 11 Home, device encryption is usually off by default — but check anyway rather than assuming. If the installer throws a BitLocker error mid-install, this is why.
Step 3: Shrink Your Windows Partition to Create Free Space
Now let’s carve out room for Omarchy. Right-click the desktop and open a terminal (or press Win + R), type diskmgmt.msc, and press Enter to open Disk Management. You’ll see your drive laid out as a set of partitions. On a typical Windows 11 machine, Drive 0 has three: a small EFI partition holding the Windows Boot Manager, the main Windows partition (usually C:), and a recovery partition at the end.
Pick the partition you want to steal space from — usually C:, but it might be D:, E:, or F: depending on how your machine was set up. Right-click it and choose Shrink Volume, then enter the amount you want to free up in megabytes:
| Space you want | Value to enter |
|---|---|
| 50 GB | 51200 |
| 100 GB | 102400 |
| 200 GB | 204800 |
Click Shrink. When it finishes you’ll see a black Unallocated block at the end of the drive. That’s the space Omarchy will install into. Don’t format it, don’t create a volume on it, don’t touch it. The Omarchy installer wants it raw.
Step 4: Download the Omarchy ISO
Head to the official Omarchy website and download the latest ISO image. Omarchy 4 shrank the ISO by over a gigabyte, so it now lands just under 6 GB — still a large download, but far quicker than previous releases. If you want to be thorough, verify the SHA256 checksum published alongside the download before flashing it.
Step 5: Create the Bootable USB Drive
Plug in your USB drive and open Rufus (Windows) or balenaEtcher (Windows or macOS). This guide uses Rufus.
- Select your USB drive under Device
- Click SELECT and choose the Omarchy ISO
- Set Partition scheme to GPT
- Set Target system to UEFI (non CSM)
- Click START and confirm the wipe warning
Everything on the USB drive gets erased, so move anything you care about off it first. When the flash completes, leave the USB plugged in and restart your computer.
Step 6: Change Your BIOS Settings
Reboot and enter the BIOS using your motherboard’s key — commonly F2, F9, F10, Del, or Esc. If you miss the window, just restart and try again. Inside the UEFI BIOS, make three changes:
- Enable USB boot if it isn’t already on
- Disable Secure Boot — this is mandatory. Omarchy isn’t a Microsoft-signed distribution, and the installer simply won’t boot with Secure Boot on. Disable TPM as well if your board exposes it.
- Set the USB drive as the first boot device in the boot order
Save your changes and exit. Your machine will now boot into the Omarchy live environment from the USB drive.
Step 7: Install Omarchy Alongside Windows
The Omarchy installer is a terminal interface, not a graphical one. Use the arrow keys to move between options and Enter to confirm. It runs entirely offline, so you don’t need to be connected to Wi-Fi to get through it. Work through the prompts in order:
- Choose your system language
- Create your user account and set a password
- Enter your full name and, optionally, an email address — you can skip the email
- Set a hostname for the machine
- Select your timezone — press / to filter and type your city name
- Review the summary and select Yes to confirm
- Select the disk where Windows lives — the same physical drive you shrank earlier
- Choose the second option: Free Space Installation
That last step is the whole reason Omarchy 4 makes dual booting easy. Instead of wiping the drive, the installer automatically finds the unallocated space you created in Step 3 and installs into it. Your Windows partition is left completely alone. You still get full LUKS disk encryption on the Omarchy partition by default, so nothing is compromised by installing this way.
Press Enter, then select Yes to confirm and format that free space. The installation runs from here. Omarchy 4 sped up installs by more than 30%, so on a fast NVMe drive this can finish in a couple of minutes.
⚠️ Important: During boot you’ll be asked for your LUKS encryption password, which is separate from your user account password. Don’t lose it — there’s no recovery path.
Step 8: Add Windows to the Limine Boot Menu
When the install finishes, your system reboots. Remove the USB drive and you’ll land in the Limine boot manager. You’ll immediately notice a problem: there’s no Windows entry. Don’t panic — Windows is untouched, Limine just hasn’t been told about it yet. Boot into Omarchy and we’ll fix it in one command.
First, two housekeeping items: connect to Wi-Fi, then update your system so you’re on the latest packages. Now open a terminal and run:
sudo limine-entry-tool --scanOn some setups the equivalent shortcut is:
sudo limine-scanThe tool scans your EFI partitions and lists every bootloader it can find. Look through the list for Windows Boot Manager — in most single-drive setups it shows up as option 2 or 3. Type the number of that entry and press Enter to add it.
Reboot, and the Limine menu will now show both Omarchy and Windows Boot Manager. Pick whichever you want at every startup.
Troubleshooting Common Problems
The installer says BitLocker is enabled. Boot back into Windows, fully disable BitLocker under Settings → Privacy & Security → Device encryption, wait for decryption to complete, and try again.
The USB won’t boot. Secure Boot is almost certainly still on. Go back into the BIOS and confirm it’s disabled, along with TPM if your board offers that toggle.
Limine can’t chain to Windows (exit code 32). Check whether Intel RST / RAID mode is enabled in your BIOS storage settings. Switching to AHCI resolves this, though be aware that changing storage mode on an existing Windows install can require repair steps.
Windows disappeared entirely after installing. The Windows EFI entry still exists on disk. Run the Limine scan again, or check your BIOS boot order — sometimes the firmware simply demoted the Windows entry rather than removing it.
No free space option appears. The installer only offers it if there’s genuinely unallocated space on the selected disk. Go back to Disk Management and confirm you shrank the volume and didn’t accidentally format the new space into a volume.
