During the process of formatting the hard disk, all data stored on it will be deleted, and then a new file system will be created. Format the drive if you want to install or reinstall Windows. We also recommend formatting the secondary (second) hard drive before using it. Sometimes a disk is formatted if you need to very quickly erase all data from it. Moreover, you can reduce the size of local disks (partitions) on your hard disk, format the freed space, and then create another local disk based on it. If you are going to sell or throw away your hard drive, the data must be permanently deleted; there are special utilities for this.
Steps
Method 1 of 4: Formatting the Primary Drive

Step 1. Back up your important files
During formatting, the operating system and all files will be deleted. Therefore, copy your important files to an external hard drive or cloud storage.
If you need to permanently delete files, go to the "Safely format a disk" section

Step 2. Insert the Windows installation DVD
You will need it to format the hard drive, because it cannot be done from a loaded operating system. Note that you can use any Windows installation disc, because you do not need to enter your product key (ignore this if you intend to reinstall Windows). If you don't have a Windows installation disc:
- Windows 7 - Enter your product key and download this system image (ISO file) here. Now burn the downloaded file to a blank DVD or USB drive using the Windows 7 USB / DVD Download Tool which can be downloaded here.
- Windows 8 - Download the Windows 8 Media Creation Tool here. It will automatically download an image of this system and create an installation DVD or USB drive (drive must be at least 4GB). Run the utility and follow the instructions on the screen.
- Windows 10 - Download the Windows 10 Media Creation Tool here. It will automatically download an image of this system and create an installation DVD or USB drive. We recommend downloading the 64-bit version of the utility. If you don't know the bit depth of your computer, read this article.

Step 3. Configure your computer to boot from an installation DVD or USB drive (not a hard drive)
Do this to launch the system installer and format the disk. Your actions depend on the current operating system of your computer.
- Windows 7 (or older version of Windows) - restart your computer and press the button to enter BIOS. The required button will be displayed on the screen with the logo of the manufacturer of the computer or motherboard when the computer starts up. In most cases, you need to press the F2, F11, F12 or Del key several times. Then find the “BOOT” menu and set the DVD or USB drive as the first boot device.
- Windows 8 (or a newer version of Windows) - Click Shut Down from the Start Screen or Start Menu. Now hold ⇧ Shift and click Restart to bring up the Advanced Startup menu on restart. From this menu, choose Troubleshoot> Advanced Options. Then click on UEFI Setup, find the BOOT menu and set the DVD drive or USB drive as the first boot device.

Step 4. Run the system installer
The installation files will be downloaded first, and then the installation process will begin. Now select your language and agree to the terms of use.

Step 5. On the page with the installation type, click Custom
This will give you the option to format your hard drive.

Step 6. Select the partition you want to format
When you have passed the first few pages in the installer window, the screen will display a list of all hard drives and their partitions. As a rule, any hard disk is divided into several partitions - for the operating system, for recovery files and, for example, for storing user files.
- On any hard drive, you can delete all partitions and combine them into one unallocated space. Remember that deleting partitions will erase all files. To delete partitions, click Disk Options> Delete.
- If you have deleted all partitions, you must first create a new partition and then format it. Select the unallocated space and click New to create a new partition. To create a section of a specific size, set it manually. Remember that you can create up to four partitions on one hard disk.

Step 7. Format the selected partition
Select a partition or drive and then click Format. If this button is not there, click Disk Options> Format. A warning will appear on the screen stating that formatting will delete all files. Confirm your actions to start formatting; it only takes a few minutes.

Step 8. Install the operating system
Since the operating system will be deleted during the formatting process, you must reinstall it (otherwise you will not be able to use the computer). When formatting is complete, continue with the Windows installation or install another operating system such as Linux. To install Windows, follow the instructions in the installer window. To install Linux, create a Linux installation DVD or USB drive. If you don't know how to install Linux, read this article.
Method 2 of 4: Formatting the Secondary Disk

Step 1. Launch the Disk Management utility
If you connected a new external or internal hard drive to your computer, format it so the system recognizes the drive. This can be done using the mentioned utility.
- Press ⊞ Win + R and enter diskmgmt.msc to launch the Disk Management utility. In Windows 8 or 10, right-click on the Start menu and select Disk Management.
- It may take several minutes for the utility window to display all mapped drives.
- If you need to permanently delete files, go to the "Safely format a disk" section.

Step 2. Initialize the disk (if prompted)
The first time you run Disk Management after connecting a new disk to your computer, you may be prompted to initialize the disk. Otherwise, skip this step.
Select the "GPT" option if the new disk has a capacity of 2 TB or more. Select the "MBR" option if the capacity of the new disk is less than 2TB

Step 3. Select the drive you want to format
The disks and their partitions appear in the Disk Management window. If you have connected a new drive, it will probably be marked as "Unallocated space". Look at the Status column for information about each section.
- The boot partition cannot be formatted because Windows is installed on it.
- Choose your disc carefully because all data on it will be erased.

Step 4. Create a section (optional)
Right-click on the desired disk and select "Create Volume" from the menu. Then follow the instructions on the screen to create a partition based on the unallocated space.

Step 5. Right-click on the disk or partition and select "Format" from the menu
The "Formatting" window will open.

Step 6. Set the formatting options
Give the drive a new name (if you like) and select the NTFS file system if you are using Windows. Now check the box next to "Quick Format". If you think the disk is damaged, check the box next to "Full format".

Step 7. Wait for the formatting to complete
Click "Format" when you specify the formatting options. The disk will be formatted in a few minutes - now you can store files and install programs on it.
Method 3 of 4: Reducing the size (shrinking) the partition

Step 1. Launch the Disk Management utility
The size of any partition can be reduced to create a new partition based on the freed (unallocated) space, for example, for storing media files. Use this method if there is a lot of free space on the partition.
Press ⊞ Win + R and enter diskmgmt.msc to launch the Disk Management utility. In Windows 8 or 10, right-click on the Start menu and select Disk Management

Step 2. Select the partition you want to reduce the size of
You can compress any partition that has a lot of free space. We recommend that you select a partition from which you can "cut" several gigabytes to make the new partition large enough. Leave enough free space on the partition to be compressed, especially if it is a boot partition. Remember that stable operation of Windows is ensured when the free space of the boot partition is at least 20% of the size of the entire partition.

Step 3. Right-click on the partition and select Shrink Volume from the menu
The utility will determine how much volume of the section is available for creating a new section; then a new window will open.

Step 4. Set the size of the new partition
A new window will display the amount (in megabytes) available for creating a new partition. Remember, 1024 MB = 1 GB. Enter the number of megabytes to be "cut" from the selected partition.

Step 5. Start the compression process
Click “Shrink” to “cut off” the specified space from the selected partition - it will appear as “Unallocated space” on the same disk where the reduced partition is located.

Step 6. Create a new partition
Right-click on the unallocated space and select New Volume from the menu. The process of creating a new section will start.

Step 7. Follow the instructions on the screen
If you want, specify the amount of unallocated space on the basis of which the new partition will be created. You can also select the letter of the section.

Step 8. Format the new partition
During the partition creation process, you will be prompted to format it. Do it now or later by following the steps outlined in the previous method.
Method 4 of 4: Format the Disk Safely

Step 1. Download the free DBAN utility
It formats hard drives and overwrites deleted data so that it cannot be recovered. Use this utility to avoid data theft if you give away, sell, or throw away a disc or computer.
- Download the free version of the DBAN utility from dban.org. This version will suit most users.
- Do not use DBAN to securely format solid-state (SSD) drives. To do this, buy the Blancco software.

Step 2. Burn the small DBAN utility to a CD / DVD
To do this, in Windows 7 and later versions of the system, right-click on the downloaded ISO file and select "Burn to disc" from the menu.

Step 3. Configure your computer to boot from the burned CD / DVD
Do this to run the DBAN utility without having to boot the system.
- Windows 7 (or older version of Windows) - restart your computer and press the button to enter BIOS. The required button will be displayed on the screen with the logo of the manufacturer of the computer or motherboard when the computer starts up. In most cases, you need to press the F2, F11, F12 or Del key several times. Then find the “BOOT” menu and set the CD / DVD drive as the first boot device.
- Windows 8 (or a newer version of Windows) - Click Shut Down from the Start Screen or Start Menu. Now hold ⇧ Shift and click Restart to bring up the Advanced Startup menu on restart. From this menu, choose Troubleshoot> Advanced Options. Then click on UEFI Setup, find the BOOT menu and set the CD / DVD drive as the first boot device.

Step 4. Launch the DBAN utility
When you set the CD / DVD drive as the first boot device, restart your computer to start DBAN. Press the ↵ Enter key on the DBAN main page to launch this utility.

Step 5. Select the drive you want to format
Use the arrow keys to highlight the drive you want to format, and then press the Space bar to select the drive. Choose the disk carefully, because you won't be able to go back, and the data will be permanently deleted. If you select the wrong drive, you can erase Windows.

Step 6. Press F10 to start the formatting process with default parameters
This formatting will delete the data permanently; the process itself can take several hours.