First, let’s clarify the title. Separate Disk means that we will install Debian on its own disk. So get your disk ready and ensure you don’t need anything on that disk because it will be formatted. Standalone means there will be no other operating system connected to the PC during the Debian installation process.
So if you want to install Debian this way and you have a Windows installation on the PC already, disconnect the Windows disk. After you finish the Debian installation, reconnect the Windows disk, and you will be able to switch between the systems - Windows and Debian - from the boot menu, or from the BIOS or UEFI or other ways. This way, we ensure that the GRUB boot loader will be installed on the Debian disk and not on the Windows disk.
Second, you will need a Debian 12 Installation Media, such as a Debian 12 Bootable USB Drive. Our article on how to create a Debian 12 Bootable USB Drive with Rufus might help you.
Third, you will need to insert the USB Drive into the computer, then restart the PC and access the BIOS or UEFI. Adjust the boot priority to boot from the USB Drive, or you can enter the boot menu and boot from the USB Drive directly. Our article on how to boot from a USB Drive might help you.
Now, from the Debian installer menu, you can see if you are booted with UEFI or BIOS mode, then choose Graphical Install and hit enter. Next, select a language and click on Continue, then select a location and click on Continue, choose your keyboard layout and click on Continue.
Here, type a hostname for the system or leave it debian as default and click on Continue, leave the domain name blank and click on Continue, as most people will not need it.
Now, type a root password for the root account twice and click on Continue. type a name for the normal account and click on Continue, type a username for the account or keep it as is and click on Continue. Type a password for the normal account twice and click on Continue.
Here, select your time zone based on the location you chose and click on Continue.
Now, let’s partition the disk. As we said, we will be installing Debian on its own disk. Just know disks in Linux will show as sda, sdb, etc., or nvme0n1, nvme1n1 etc., and partitions will show as sda1, sda2 etc., or nvme0n1p1, nvme0n1p2.
Choose the partitioning method, Guided - use entire disk, then click on Continue and choose the disk then click on Continue, then keep the default option All files in one partition then click on Continue, then Debian will partition the disk automatically.
Or choose the partitioning method, Manual, and if you have a brand new drive, the drive will show without partition table or free space. Just double click on the disk and select Yes to create an empty partition table or free space then click on Continue, and if you get the partition table type screen choose GPT or MBR / MSDOS, GPT for UEFI, MBR / MSDOS for BIOS.
If you have a used disk, you might see a few partitions already exist. Just double click on the partitions one-by-one and select Delete this partition then click on Continue.
The partitions for UEFI boot, are as follows in order: an EFI System Partition: 500 MB in Size or More, a System Partition: Max Size Minus Swap Size, a Swap Partition: Same Size Of Your RAM or Double it if you have low memory RAM.
(Swap partition is not required but recommended, instead of it you can set up a swap file later).
Now, double click on the free space to create the first partition which will be the EFI System Partition also known as ESP, keep the default option Create a new partition selected and click on Continue, now give the partition a size, for the ESP is recommended to be 500 MB at least and click on Continue, keep the default option Beginning selected and click on Continue, at the partition settings screen double click on Use as option and select EFI System Partition and click on Continue, then select Done setting up this partition and click on Continue.
Now, double click on the rest of the free space again to create the second partition which will be the System partition, keep the default option Create a new partition selected and click on Continue, now give the partition a size, for the system partition give it max size minus the size of the swap partition we will create later if you plan on creating one and click on Continue, keep the default option Beginning selected and click on Continue, at the partition settings screen double click on Use as option and select Ext4 journaling file system and click on Continue, then double click on Mount point option and select / or the root file system and click on Continue then select Done setting up this partition and click on Continue.
Now, double click on the rest of the free space again to create the third partition which will be the Swap partition, keep the default option Create a new partition selected and click on Continue, now give the partition a size, which should be the rest of the free space after doing some math to create the second partition and click on Continue. A Swap Partition can be the same size of your RAM or double it if you have low memory RAM (Swap partition is not required but recommended, instead of it you can set up a swap file later). At the partition settings screen double click on Use as option and select Swap area and click on Continue, then select Done setting up this partition and click on Continue.
The partitions for BIOS boot, are as follows in order: a System Partition: Primary, Max Size minus Swap Size, a Swap Partition: Logical, same size of your RAM or double it if you have low memory RAM (Swap partition is not required but recommended, instead of it you can set up a swap file later).
Now, select Finish partitioning and write changes to disk and click on Continue, then select Yes to write the changes to disk and click on Continue.
Then, at Configure the package manager which is called ‘apt’ in Debian and Debian-based Linux distributions, select No for Scan extra installation media and click on Continue. Select Yes for Use a network mirror and click on Continue. choose a mirror country. I will go with the United States and click on Continue, then choose a mirror archive. I will go with deb.debian.org and click on Continue.
For Participate in the package usage survey select No and click on Continue.
for Software selection select the desktop environment, DE for short, you want to use, popular options can be GNOME, KDE Plasma, Cinnamon, lightweight options can be XFCE, LXQT, and others, you can also select multiple desktop environments and switch between them at the login screen. I will go with GNOME desktop environment. If you need an SSH server or web server you can select these options, and keep Standard system utilities selected, and click on Continue. Just know that you can install any of the desktop environments later by typing tasksel in the terminal.
Finally, click on Continue to reboot.
Now, at the login screen if you installed multiple desktop environments you can switch between them by clicking on the gear icon in this case, and choose the DE you want then enter the password for the user account you created, then hit enter, and you will be at the desktop.