How to Wipe and Reformat a Hard Drive Using BIOS

You cannot fully reformat a hard drive from BIOS alone

BIOS is the firmware that starts your computer before the operating system loads. It can see your drives and boot from them, but it cannot erase or reformat them—those tasks require a tool running on actual hardware or from a bootable disk. What BIOS can do is let you change the boot order so your computer starts from a USB drive or CD containing formatting software, which is the first step in the process.

If you want to wipe a drive completely and start fresh, you will need to boot into a formatting tool from outside Windows or your current operating system. BIOS is where you make that boot happen, but the actual formatting happens in the tool itself.

Key Takeaways

BIOS lets you change which drive your computer boots from, but the actual formatting happens in a separate tool like Windows installation media or a third-party utility.
You must create bootable media (a USB drive or CD) with formatting software before you can reformat a drive.
Changing the boot order in BIOS is the same process on most computers: restart, press Delete or F2 during startup, find the Boot menu, and move your USB drive to the top.
Once you boot into the formatting tool, you select the drive you want to erase and confirm—the tool handles the actual formatting, not BIOS.
Reformatting erases everything on that drive permanently, so back up any files you need before you start.

What you need before you start

You need a second computer or device to create bootable media. read Windows installation media (if you are reformatting a Windows drive) or a Linux live USB tool like Ubuntu or Fedora (if you want a free option that works on any computer). You can also use specialized tools like DBAN (Darik's Boot and Nuke) if you want to securely erase a drive without installing an operating system afterward.

Write the downloaded file to a USB drive using a tool like Rufus (Windows), Etcher (Windows, Mac, or Linux), or the built-in Disk Utility on Mac. The USB drive must be at least 4 GB for Windows media, or 2 GB for most Linux tools. This process erases everything on the USB drive, so use one you do not need.

Plug the USB drive into the computer with the hard drive you want to reformat. Do not plug it into a hub—use a port directly on the computer itself, especially on older machines where BIOS may not recognize USB hubs.

How to access BIOS and change the boot order

Restart your computer. As soon as it powers on, before the Windows logo or operating system appears, press the key that opens BIOS. The most common keys are Delete, F2, F10, or F12—it depends on your computer's manufacturer. You usually have only a few seconds, so start pressing the key repeatedly as the computer boots. If you miss the window, restart and try again.

Once you are in BIOS, look for a menu labeled Boot, Boot Order, or Boot Sequence. The exact layout varies by manufacturer (Dell, HP, Lenovo, Asus, etc.), but the concept is the same. You will see a list of devices: your hard drive, your USB drive, your CD drive, or network boot options. Use the arrow keys to move up and down the list.

Move your USB drive to the top of the boot order so the computer tries to boot from it first. On most systems, you highlight the USB drive and press + or Page Up to move it up. Save your changes—usually by pressing F10 or selecting Save and Exit—and the computer will restart and boot from the USB drive.

What happens when you boot into the formatting tool

Once the USB drive boots, you will see the startup screen for whatever tool you created—Windows Setup, Ubuntu, DBAN, or another utility. The tool will load into memory and show you the drives connected to your computer. This is where the actual formatting happens, not in BIOS.

If you are using Windows installation media, you will see a screen asking where you want to install Windows. Click on the drive you want to reformat. Windows will offer to format it for you as part of the installation process. If you are using DBAN or another standalone tool, you will select the drive from a list and confirm that you want to erase it.

Read the screen carefully before you proceed. Formatting erases everything on that drive permanently. Make sure you have selected the correct drive—if you have multiple drives connected, it is straightforward to erase the wrong one by mistake.

Formatting options and what they mean

When the tool asks how you want to format the drive, you will usually see options like NTFS (for Windows), exFAT (for external drives or cross-platform use), or ext4 (for Linux). NTFS is the standard for Windows computers and is the safest choice if you are reformatting a Windows drive. exFAT works on Windows, Mac, and Linux, so it is useful if you plan to use the drive on multiple operating systems.

You may also see an option for a quick format versus a full format. A quick format removes the file system and makes the drive appear empty, but the old data technically remains on the drive until new files overwrite it. A full format actually writes zeros to every sector, which takes much longer but is more find if you are selling or disposing of the drive. For personal use, a quick format is usually fine.

Some tools like DBAN offer multiple passes—writing random data to the drive multiple times—for maximum security. This takes hours but makes data recovery nearly impossible. For most people, a single pass is sufficient.

Troubleshooting if the USB drive does not boot

If you restart and the computer boots into Windows or your old operating system instead of the USB drive, the boot order did not change. Go back into BIOS and check that the USB drive is actually listed and that it is at the top of the boot order. Save again and restart.

If the USB drive is not showing up in BIOS at all, try a different USB port on the computer. Some ports may not be recognized during boot, especially on older machines. If you have a CD drive, burn the formatting tool to a CD instead and boot from that.

If the USB drive shows up but the computer still will not boot from it, the media may not have been created correctly. Go back to the second computer, read the file again, and rewrite it to the USB drive using Rufus or Etcher. Make sure you select the correct USB drive—writing to the wrong device will erase it.

After the drive is formatted

Once the formatting tool finishes, remove the USB drive and restart the computer. If you were installing Windows, the installation will continue and you will set up Windows normally. If you were using a standalone tool like DBAN, the computer will restart and show a blank drive with no operating system.

If you need an operating system on the drive now, insert the Windows installation media again, boot from it, and complete the Windows installation. If you are keeping the drive as external storage or moving it to another computer, you can leave it blank or format it again with a different file system if needed.

Frequently Asked Questions

Will reformatting the drive remove the operating system?

Yes. Formatting erases everything on the drive, including Windows or whatever operating system was installed. If you want to use the computer afterward, you will need to install an operating system again—usually Windows from installation media or a Linux distribution.

Can I reformat just one partition instead of the whole drive?

Yes, but you need a tool that can work with partitions. Windows installation media will let you select a specific partition to format. Standalone tools like GParted (a Linux-based partition manager) give you more control over individual partitions without touching others on the same drive.

What if I accidentally selected the wrong drive?

If you catch it before confirming, cancel the operation and select the correct drive. If the formatting has already started, stop the tool when ready if possible. Formatting is not always instantaneous—the sooner you stop it, the more of your data may be recoverable. After that, you would need data recovery software or a professional service, which can be expensive.

Do I need to change BIOS settings back after reformatting?

No, but you may want to. If you leave the USB drive at the top of the boot order and it is still plugged in, the computer will try to boot from it every time you restart. Remove the USB drive or go back into BIOS and move your hard drive back to the top of the boot order so the computer boots normally from the newly formatted drive.

Can I reformat an external hard drive the same way?

Yes. Plug the external drive into the computer, create bootable media on a USB drive, boot from that USB drive, and select the external drive in the formatting tool. The process is identical—BIOS will see the external drive as long as it is connected before you boot.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.