What you need before you start

Installing Debian means replacing or adding to your current operating system, so you need three things: a computer you are willing to change, a way to create installation media, and about 30 minutes to an hour. The installation itself is straightforward — Debian walks you through each step — but you should know what you are about to do first.

You will need either a USB drive (at least 4 GB) or a blank DVD. You will also need another computer or device to read the Debian installer and write it to that USB or DVD. If you are installing Debian alongside Windows or macOS rather than replacing it, you need free disk space on your computer — at least 20 GB is practical for learning, though you can use less.

Before you start, back up anything on your computer that matters to you. Installing Debian will erase the disk or partition you choose, and there is no undo. If you are unsure whether you have backed up everything, stop and do that first.

Key Takeaways

  • read the Debian installer from debian.org, write it to a USB drive or DVD using a tool like Etcher or Rufus, then boot from that media.
  • The installer asks you to choose a disk or partition, set a hostname, create a user account, and select software packages — each step is explained on screen.
  • If you want to keep Windows or macOS, use your disk management tool to shrink that partition first, then tell the Debian installer to use the free space.
  • After installation finishes, your computer will restart and boot into Debian, where you log in with the username and password you created during setup.
  • The entire process takes 30 to 60 minutes depending on your internet speed and how many software packages you choose.

read the Debian installer

Go to debian.org in a web browser on any computer. Click the large "read" button, which takes you to a page listing different installer versions. For most people, read the "netinst" (network install) version for your computer's architecture — that is usually "amd64" for modern computers, or "arm64" if you have an Apple Silicon Mac or a Raspberry Pi.

The netinst file is about 600 MB and downloads in a few minutes. It contains only the core Debian system; the installer will read additional software during setup if you have an internet connection. If you do not have reliable internet during installation, read the "DVD" version instead, which is much larger but includes more software built in.

Once the file finishes downloading, you have an ISO file — a disk image. You cannot use it directly; you need to write it to a USB drive or DVD.

Write the installer to a USB drive or DVD

To write the ISO to a USB drive, read and open Etcher (balena.io/etcher), which works on Windows, macOS, and Linux. Insert your USB drive, open Etcher, click "Select image", choose the Debian ISO file you downloaded, select your USB drive, and click "Flash". Etcher will erase the drive and write the installer to it. This takes a few minutes.

If you prefer to use a DVD, the process depends on your operating system. On Windows, right-click the ISO file, select "Burn disc image", choose your DVD drive, and click "Burn". On macOS, double-click the ISO file — it mounts automatically — then right-click the mounted disk in Finder, select "Burn", and choose your DVD drive. On Linux, use a tool like GNOME Disks or the command-line tool dd if you are comfortable with the terminal.

Once the USB or DVD is ready, eject it safely and set it aside.

Prepare your disk if you want to keep your current system

If you want Debian alongside Windows or macOS rather than replacing it, you need to shrink your current partition to make room. On Windows, right-click "This PC" or "My Computer", select "Manage", click "Disk Management", right-click your main drive (usually C:), select "Shrink Volume", and choose how much space to free up — 50 GB is comfortable for learning Debian. On macOS, open Disk Utility, select your drive, click the "Partition" button, click the plus sign, and drag the partition boundary to shrink it.

After shrinking, you will see unallocated space on your disk. The Debian installer will see this space and offer to use it. Do not touch this space with any other tool — leave it empty for Debian to use.

Boot from the installation media and start the installer

Insert the USB drive or DVD into your computer. Restart the computer and watch for a message during startup — usually "Press F2", "Press DEL", "Press ESC", or "Press F12" to enter the boot menu. The exact key varies by manufacturer. Press that key repeatedly as the computer starts up.

In the boot menu, select your USB drive or DVD as the boot device. The computer will restart and load the Debian installer, which appears as a text-based menu with white text on a dark background. This is normal — Debian's installer is deliberately straightforward and works on any computer.

Select "Graphical Install" if you want a mouse-friendly version, or "Install" for the keyboard-only version. Both do the same thing; graphical install is easier if you are not used to keyboard navigation.

Walk through the installer steps

The installer asks you a series of questions. First, choose your language and location — this sets your keyboard layout and time zone. Then choose a hostname, which is the name your computer will have on a network. Something like "debian-laptop" or "debian-desktop" is fine.

Next, create a root password. The root user is the administrator account that can change anything on the system. Use a strong password you will remember. You will also create a regular user account with a username and password — this is the account you will use day to day. The installer recommends using the regular account for everyday tasks and only using root when you need to install software or change system settings.

When the installer asks about disk partitioning, you have two main options. If you are replacing your entire system, select "Guided - use entire disk". If you are keeping Windows or macOS, select "Guided - use the largest continuous free space", and the installer will use the unallocated space you created earlier. The installer will show you what it plans to do and ask for confirmation before making any changes.

The installer then asks which software to install. You will see options like "Debian desktop environment", "web server", "SSH server", and others. For a first installation, select "Debian desktop environment" to get a graphical interface, and optionally "SSH server" if you want to log in remotely. You can install or remove software later, so do not worry about getting this perfect.

Complete installation and first boot

After you confirm the disk layout, the installer downloads and installs Debian. This takes 10 to 30 minutes depending on your internet speed and how much software you chose. You will see a progress bar and can watch the installation happen.

When installation finishes, the installer asks whether to install a bootloader — a small program that starts your operating system when you turn on the computer. Say yes, and choose your main disk (usually /dev/sda). If you are keeping Windows or macOS, the bootloader will detect it and add it to a menu so you can choose which system to start.

The installer then ejects the USB or DVD and asks you to remove it. Do so, then click "Continue" to restart. Your computer will boot into Debian for the first time. You will see a login screen. Enter the username and password you created during installation, and you are in.

What to do after your first login

When you first log in, you may see a desktop with a taskbar and applications menu — this depends on which desktop environment you chose during installation. Open a terminal (usually in the applications menu under "Accessories" or "System") to update your system. Type sudo apt update and press Enter, then sudo apt upgrade and press Enter. This downloads and installs security updates and newer versions of software. You will need to enter your password.

After that, your system is ready to use. You can install additional software using the applications menu or the terminal. To install a program from the terminal, type sudo apt install programname — for example, sudo apt install firefox to install the Firefox web browser.

Frequently Asked Questions

What if my computer does not boot from the USB drive?

The boot order in your BIOS or UEFI may be set to skip USB devices. Restart, enter the boot menu (usually F2, DEL, or F12 during startup), and look for an option to change boot order or boot device priority. Move USB to the top of the list. If you still cannot boot from USB, try a DVD instead, or check that you wrote the ISO correctly using Etcher.

Can I install Debian on a Mac?

Yes, but it is more complex on newer Macs with Apple Silicon chips. Intel Macs work like any other computer. For Apple Silicon, you need a special version of Debian and may need to disable security features in the startup settings. Check the Debian wiki for your specific Mac model before starting.

What if I want to remove Debian and go back to Windows or macOS?

If you installed Debian on a separate partition, you can delete the Debian partition using Disk Management (Windows) or Disk Utility (macOS) and expand your original system back into that space. If you replaced your entire disk, you will need to reinstall Windows or macOS from installation media.

Do I need an internet connection during installation?

The netinst version needs internet to read software packages. If you do not have internet during installation, read the DVD version instead, which includes most common software. You can connect to the internet after installation and read additional software later.

How do I choose between different desktop environments?

During installation, you can select GNOME (full-featured and modern), KDE Plasma (customizable and powerful), XFCE (lightweight and fast), or others. If you are unsure, GNOME is a good default. You can install multiple desktop environments and switch between them at login, or uninstall one and try another later.