Disk Management in Windows
You need Disk Management when you add an unformatted hard disk drive (removable or local) to your computer, want to change drive letter for a drive or partition, or change partition size. If you haven't already done so, read the Memory and hard disks article to find out basic information about hard disks and partitions.
The most usual case is adding a new, unformatted hard disk. It may be your new external USB hard disk drive (though majority of these came preformatted) or a new secondary local hard disk for large files, such as videos. Windows does not assign a letter to an unformatted disk, you will have to initialize it first, then create a partition and format it.
Windows creates partitions as volumes, so you also have the ability to reduce and increase the size of partitions on the fly, without losing your data. Well, in Windows Vista and later, at least. 
The terms "partition" and "volume" mean the same thing in this article and are used interchangeably.
After using and closing Disk Management you might see some pop-up windows about formatting a partition before using it and some AutoRun/AutoPlay windows. Just close these - most probably these tasks have already been accomplished.
Those who have Windows 8 or 8.1 installed on SSD (Solid-State Drive) should turn off built-in Disk Defragmenter: there is a known bug in it that starts defragmenting (instead of using the TRIM command) SSD-s. This will lead to decreased lifetime and failure of the drive.
Starting Disk Management in Windows
Right-click (or tap and hold) Computer or This PC icon on Desktop or Start menu/screen and click Manage.
In Windows 8 and 8.1, you can use keyboard shortcut Windows Key+X to open Quick Links menu (a list of system tools) and click Disk Management there.
Windows Vista users should click Continue in the most beloved User Account Control window.
Computer Management window opens. Click Disk Management on the left side, in the Storage section.
Initializing and formatting new disks in Windows
If you have added a new, unformatted hard disk to your computer, an initialization wizard opens right after clicking on Disk Management.
Click here to show or hide disk initialization instructions for Windows XPIn Windows XP, click Next in the Initialize and Convert Disk Wizard.
Select the disk you want to initialize (in most cases you have only one here) by checking the corresponding check box. Then click Next.
This screen applies to Windows XP Professional users only. For most users, basic disks are absolutely fine. Furthermore, Windows 95, 98, Me and Windows XP Home users cannot use dynamic disks at all, so for compatibility reasons it is best to leave all boxes unchecked and click Next.
Disk initialization is now complete. Click Finish.
Click here to show or hide disk initialization instructions for Windows Vista, 7, 8 and 8.1
Make sure your new disk is selected under Select disks list in the Initialize Disk wizard. For most disks, leave MBR (Master Boot Record) partition style selected. For very large disks (more than 2 TB (terabytes) in size), select GPT (GUID Partition Table) instead. Please note that older Windows versions, such as Windows 95, 98, Me, NT and 2000 cannot use GPT partition style or very large partitions. Only Windows XP and later support GPT.
Click OK.
A new basic disk will be created. Windows Vista, 7, 8 and 8.1 do not offer to create dynamic disks like Windows XP did. This is fine, because not many of us need dynamic disks anyway.
Creating a partition on the new disk and formatting it
Formatting is required for new, unformatted disks only. If you just initialized a drive that was used in another computer and the drive contains data, skip this step altogether - your disk is ready for use.
A new, unformatted disk needs to have at least one partition to become usable. In Windows Vista, 7, 8 and 8.1, partitions are created within volumes and you start by creating one.
Click here to show or hide instructions on creating and formatting a new partition in Windows XPTo create a new partition, find your new disk from the bottom part of the Disk Management console. It usually contains word "Unallocated" in it.
Right-click on the disk and select New Partition...
New Partition Wizard opens. Click Next.
Leave Primary partition selected and click Next. Home users do not normally need Extended partitions.
In most cases, it is best to allocate all available disk space to the new partition. Click Next again.
Next you need to assign a drive letter to the new partition. By default, Windows XP offers the first available drive letter not in use by any other local drive. Drive letters "A" and "B" are reserved for floppy drives, "C" is usually the drive where your Windows XP installation and documents are and "D" is probably your CD/DVD drive.
As the default drive letter is probably fine, click Next here.
While New Partition Wizard does not display drive letters already assigned to local disks, it still displays letters assigned to network shares (network connections). If you happen to have network shares connected, and New Partition Wizard offers a drive letter that is in use by a network drive, you will see a warning that the drive letter is already mapped to a network share. Click No here and select a drive letter that is not currently in use. Remember, you can see all assigned drive letters by opening My Computer (press WINDOWS KEY+E for this).
Click Format this partition with the following settings and specify parameters.
- File system - NTFS is the best choice for the hard disks that are inside your computer case (local disks). If you are formatting some USB external hard disk and you want to connect it to Windows 98 or Me PC-s, select FAT32 instead - this improves compatibility. For USB flash drives, FAT32 is mostly the best selection, unless you need to copy files larger than 4 gigabytes. For the latter case, select NTFS.
- Allocation unit size - in most cases, leave Default selected. Default is 4096 bytes (4 kilobytes). This works best for disks that contain all sorts of files - documents, pictures, videos, etc. If you are planning to use the drive for large video files only, you can select the largest one available - 64kB (kilobytes). This improves file performance for large files, but this also wastes loads of disk space for small files, so put only large files on that disk!
- Volume label - this is a descriptive name for your new drive - Videos, Backups, etc. You can also leave this field empty. You can see the label in My Computer - for unlabeled hard disk this would be "Local Disk" or "Removable Disk" (depending on its type), for a labeled one this could be "Videos " or "Backups" or whatever you specify. It is wise to name a drive or partition as this makes easier to distinguish it in advanced scenarios - troubleshooting, using DiskPart utility, etc. You can also set a name for any existing partition or drive without losing data.
- Perform a quick format - always check this box, this decreases formatting time drastically.
- Enable file and folder compression - if you are formatting a local (not removable) disk that will have NTFS file system and the disk will contain mainly usual documents (spreadsheets, pictures, presentations, etc), you can turn this on. This will compress the files and you can use more space than your drive offers - 2 to 10 times for Microsoft Word documents, Excel spreadsheets, PowerPoint presentations and plain text files, much less for programs, photos (jpg, png, gif) and music files (mp3, aac). Compression does not mean a noticeable reduction in disk speed.
If you will use the disk for video files, compression has no effect and you can leave the box unchecked.
You cannot use file and folder compression if file system type is not NTFS or if allocation unit size exceeds 8192 bytes (8 kilobytes).
Mostly the defaults are fine, so click Next.
New Partition Wizard has now asked all the questions, click Finish to close it. After this, your new partition will be formatted and the selected drive letter will be assigned to it.
Click here to show or hide instructions on creating and formatting a new partition in Windows Vista, 7, 8 and 8.1
To create a new partition, find your new disk from the bottom part of the Disk Management console. It usually contains word "Unallocated" in it.
Right-click on the disk and select New Simple Volume...
New Simple Volume Wizard opens. Click Next.
In most cases, it is best to allocate all available disk space to the new volume. Click Next again.
Next you need to assign a drive letter to the new partition. By default, Windows Vista and later offer the first available drive letter not in use by any other local or network drive. Drive letter "A" is reserved for floppy drives, "C" is usually the drive where your Windows installation and documents are and "D" is probably your CD/DVD drive.
As the selected drive letter is probably fine, click Next here.
Click Format this partition with the following settings and specify parameters.
- File system - NTFS is the best choice for the hard disks that are inside your computer case (local disks) and for external disks that you want to use for backups. If you are formatting some USB external hard disk and you want to connect it to Windows 98 or Me machines, select FAT32 instead - this improves compatibility. For USB Flash drives, FAT32 is always the best selection, unless you need to copy files larger than 4 gigabytes. For the latter case, select NTFS.
- Allocation unit size - in most cases, leave Default selected. Default is 4096 bytes (4 kilobytes). This works best for disks that contain all sorts of files - documents, pictures, videos, etc. If you are planning to use the drive for large video files or backups, you should select 16K (kilobytes). This improves file performance for large files, but this also wastes loads of disk space for small files, so put only large files on that disk!
- Volume label - this is a descriptive name for your new drive/partition - Videos, Backups, etc. You can also leave this field empty. You can also see the label in My Computer - for unlabeled hard disk this would be "Local Disk" or "Removable Disk" (depending on its type), for labeled one this could be "Videos" or "Backups" or whatever you specify. It is wise to name a drive or partition as this makes easier to distinguish it in advanced scenarios - troubleshooting, using DiskPart utility, etc. You can also set a name for any existing partition or drive without losing data.
- Perform a quick format - always check this box, this decreases formatting time drastically.
- Enable file and folder compression - if you are formatting a local (not removable) disk that will have NTFS file system and the disk will contain mainly usual documents (spreadsheets, pictures, presentations, etc), you can turn this on. This will compress the files and you can use more space than your drive offers - 2 to 10 times for Microsoft Word documents, Excel spreadsheets, PowerPoint presentations and plain text files, much less for programs, photos (jpg, png, gif) and music files (mp3, aac). Compression will not mean a noticeable reduction in disk speed.
If you will use the disk for video files, compression has no effect and you can leave the box unchecked.
You cannot use file and folder compression if file system type is not NTFS or if allocation unit size exceeds 8192 bytes (8 kilobytes).
In most cases, the defaults are fine, so click Next.
New Simple Volume Wizard has now asked all the questions, click Finish to close it. After this, your new partition will be formatted and the selected drive letter will be assigned to it.
"The system cannot find the file specified" error during drive initialization
Some users encounter the dreaded "The system cannot find the file specified" error while trying to initialize their new or existing disks. This message does not mean your disk is broken or unusable.
The error pops up mainly for older IDE (aka EIDE, ATA or PATA) drives that use jumper blocks to determine whether the drive is in slave or master mode. For example, when you have a slave drive inside a PC, you then put the drive into a IDE-to-USB drive conversion kit and connect it to another PC, you might just end up with "The system cannot find the file specified" error.
Disconnect the drive and set its jumper shunt (aka just "jumper") to Master or Single Drive position to get rid of this error. The jumper block guide is most probably on the drive's enclosure. If not, use the almighty Google (or its privacy-aware clone DuckDuckGo) to find instructions for the drive jumper placement.
SATA drives do not have jumper blocks anymore. The jumper shunts on IDE drives are mainly used for determining boot order: Windows always looks for boot record on master drive first.
If you somehow experience this error with a new, unformatted SATA drive, then please read the Partition disks with GParted Live article for solving this problem. But remember, this method will erase all data on the drive!
Clearing read-only attributes for disks and volumes in Windows Vista, 7, 8 and 8.1
In rare cases you might see an error message such as "The operation did not complete because the media is write-protected" or "The volume is read only" while trying to format or initialize a disk. This happens when someone or some program has marked the disk or volume/partition read-only.
In Windows XP, there is no easy solution available - Microsoft has provided no tools for this. Follow instructions in the Clear disk or volume read-only attribute with Windows 7 DVD article to make the disk or volume writable.
In Windows Vista, 7, 8 and 8.1, open elevated Command Prompt. Windows Vista and 7 users should open Start menu using keyboard shortcut Ctrl+Esc and type "cmd" into Search box. Then right-click the result and select Run as administrator.
Windows 8 and 8.1 users should use keyboard shortcut Windows Key+X to open Quick Links menu and click Command Prompt (Admin). In Windows 8.1, you must first replace PowerShell items with Command Prompt ones in Taskbar and Navigation properties.
Alternatively, open Apps search/Search everywhere using keyboard shortcut Windows Key+Q and type "cmd" into Search box. Then right-click Command Prompt and select Run as administrator from App bar.
User Account Control pops up. Click Continue or Yes.
In the Command Prompt window, type diskpart and press Enter key on keyboard.
The following steps are the same for both volumes and disks - just replace "volume" with "disk" if you need to clear the read-only attribute for a disk.
Type list volume and press Enter to see all available volumes. Find the troublesome one (based on its drive letter and size - the Ltr and Size columns), type select volume <volume number> and press Enter. In this example, Volume 5 is write-protected and formatting failed. That's why its File System (the Fs column) is "RAW".
Now run attributes volume to verify the volume/partition really is marked read-only. Note that you should not include the volume's number this time, because it is already selected.
Read-only is set, so type attributes volume clear readonly and press Enter.
You can repeat the same process for other volumes on the disk, or the disk itself to be absolutely sure nothing is preventing you from formatting the volume/partition.
After you're done, type exit and press Enter. Then close Command Prompt and return to Disk Management. Right-click the volume you just made writable and select Format.
Renaming existing partitions or drives in Windows / File Explorer
You can set a descriptive volume label (or name) for any fixed or removable drive (this includes hard drives, USB flash drives, but not read-only media such as CD-R or DVD-R). Easier distinguishing between existing partitions and drives might come in handy in advanced usage scenarios where you need to use the DiskPart utility for expanding or shrinking drives, or when you need to use Command Prompt for Windows troubleshooting.
Renaming a drive or partition will not affect any data on it: you will not lose your files.
Open Windows / File Explorer (keyboard shortcut Windows Key+E), browse to Computer / This PC if needed and then right-click (or tap and hold on touch-screens) the drive or partition you want to rename. Select Properties from the menu, type a name into the topmost field of General tab and click OK.
For example, if you have a dual-boot computer, set the name of operating system (such as "Windows 7" or "Windows 8.1") here; if you have many USB sticks, set the manufacturer and size for a name (such as "Apacer 16GB"); or set a name for secondary drives or partitions (such as "Data" or "Videos").
You should only avoid the name "SYSTEM", as this is used for hidden boot and recovery environment partition since Windows Vista.
Now the name is visible both in Windows / File Explorer and in command-line utilities, such as DiskPart. See, much easier to know which drive is which. 
Changing drive letters for existing drives/partitions in Windows
If you have mistakenly assigned a wrong drive letter for your new drive or if you want to change a drive letter for some other drive, right-click on the disk/partition and select Change Drive Letter and Paths... command.
Please note that you cannot do this for the partition/drive that contains your current Windows installation - this would make your computer inoperable. Neither should you change drive letters for disks where you have programs installed - the software might stop working properly after this.
Click Change.
Select a new available drive letter from Assign the following drive letter box and click OK.
You might see a warning that some programs relying on drive letters might not run correctly. Make sure you have no programs installed on the disk you are changing drive letter for.
If there are no programs on the disk, click Yes. Otherwise, cancel the operation by clicking No.
Converting a FAT/FAT32 volume/partition to an NTFS volume/partition without losing data in Windows
Many preformatted external hard disks come with FAT32 file system to be compatible with older operating systems such as Windows 98 and Me. Often this is no problem at all, but FAT32 file system is not good for large video and backup files. To be exact, you cannot create a file bigger than 4 gigabytes (GB) on a FAT32 volume. So creating a full DVD image or copying a large archive file for backup purposes is not possible. Also, you cannot back up your Windows Vista, 7, 8 or 8.1 computer on a FAT32 drive using the built-in Windows Backup program.
Luckily, you can convert the partition to an NTFS partition without losing any files or folders on the partition. This removes the 4GB file size limit, but also makes the drive incompatible with Windows 98 and Me computers. Well, 98 and Me are really old anyway. 
Please remember that there is no easy way back - you cannot convert an NTFS volume back to FAT32 volume without losing data! There are such programs available, but most of these are not free of charge.
If you are sure you need NTFS, open My Computer using keyboard shortcut Windows Key+E. Find the volume you need to convert and write down its label and drive letter. Label appears before drive letter and a colon in brackets. In this example, volume label is "FATTY" and drive letter is "E:". If there is no volume label specified, a general description such as "Local Disk" or "Removable Disk" will be used instead.
Also make sure there is at least 10 megabytes of free space on the disk before converting.
Next, close My Computer and all other open programs.
In Windows XP, use keyboard shortcut Windows Key+R to open Run dialog (or open Start menu and click Run). Type "cmd" and click OK.
In Windows Vista and 7, open Start menu by pressing Windows Key or by clicking Start button. Type "cmd" into Search box, right-click cmd.exe in search results and select Run as administrator. This will open so-called elevated Command Prompt (Command Processor).
In Windows 8 and 8.1, use keyboard shortcut Window Key+X to open Quick Links menu and click Command Prompt (Admin). In Windows 8.1, you must first replace PowerShell items with Command Prompt ones in Taskbar and Navigation properties.
Alternatively, open Apps search/Search everywhere using keyboard shortcut Windows Key+Q and type "cmd" into Search box. Then right-click Command Prompt and click Run as administrator in App bar.
In Windows Vista and later, User Account Control will ask whether you want to allow the program make changes to your computer or not. Click Continue or Yes.
A black Command Prompt window will open. Type the following command: convert <drive letter>: /FS:NTFS /X
Replace <drive letter> with the letter of the drive you wrote down earlier ("E" in this example) and make sure you type a colon right after it.
Convert will check the current file system for the specified drive and ask for its volume label for added security. If the volume label you wrote down was not "Local Disk" or "Removable Disk", type the label now; else leave it empty. Press Enter key to confirm.
If the label was correct, Windows will check the disk for errors. This might take some time.
If the disk is fine, converting will begin. This might take up to half an hour, depending on the disk size. You will see Conversion complete after this.
If the disk check failed, you should run the following command in the same Command Prompt window: chkdsk <drive letter>: /F /X
Again, replace <drive letter> with the letter of the disk you want to convert, and make sure there is a colon right after it. Please note that the command cannot be completed on a system disk (where Windows is installed) or a disk that has open files - this will cause a message stating "Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)". Press y key and then press Enter to schedule a disk check, then restart your computer, wait for the disk check to complete and log back on. Then run convert <drive letter>: /FS:NTFS /X in Command Processor window again.
In case the disk is not locked and computer restart is not needed, repeat the command until you see "Windows has checked the file system and found no problems" message. Then run convert <drive letter>: /FS:NTFS /X again.
Deleting a volume/partition in Windows
If you want to delete a partition or a volume, please make sure there is nothing important on it first. Deleting it will remove all files and folders on it and leave it unformatted.
Right-click the partition or volume you want to remove and click Delete Partition... or Delete Volume...:
A warning window will appear notifying you that you will lose all data on it. Click Yes if you are sure you want to delete the partition or volume.
If you accidentally deleted a wrong volume, you can use Find and Mount on www.winhelp.us Data Recovery CD/USB for restoring files and folders.
Shrinking a volume/partition in Windows Vista, 7, 8 and 8.1
Sometimes you might want to repartition your drive to have two partitions inside one hard disk. Maybe you want a separate partition for your videos so that these files do not affect important documents when the partition is full. Or maybe you want to dedicate some disk space for backups.
To shrink a volume or partition, there must be some free space available on it and the partition must be formatted as NTFS. If you have a 250-gigabyte disk with around 70 gigabytes used of it, you can divide the disk into two 125-gigabyte partitions, or one partition with 75 gigabytes and one with 175 gigabytes disk space. The numbers are really up to you, but always leave some space for growth on both volumes.
You should also defragment the disk before shrinking it, because if there are files scattered all over the disk, the partition size cannot be reduced even when there is plenty of free disk space available. Partitions and volumes must be allocated consecutively, not like one piece in the middle of the disk and another piece somewhere in the beginning of the disk.
Oh right, you will lose some disk space after dividing a disk into two or more partitions because some disk space will be used for describing the data, partitions and volumes available on it. Don't say I didn't warn you!
In Windows Vista and newer, this process is easy and all wizard-driven; in Windows XP this is not possible with tools Microsoft has provided, but you can use EaseUS Partition Master's Resize/Move Partition command. The free program is also available on my Data Recovery CD/USB.
Right-click on the NTFS-formatted volume or partition you want to reduce and click Shrink Volume...:
Windows will verify that there is sufficient adjacent free space on the volume. This takes from a few seconds to several minutes.
In the Enter the amount of space to shrink in MB box the free disk space available will be displayed. You can decrease it to your likings. Here I have 30714 megabytes (or around 30 gigabytes) available, but I just need some 10000 megabytes (a little less than 10 gigabytes) disk space for the second partition.
After setting the shrink space, click Shrink.
Now you will see two volumes on the Disk, with one of them Unallocated (unpartitioned and unformatted). You can now create a partition and format it.
Extending a partition or volume in Windows
You can also make a NTFS-formatted volume/partition bigger if you have free, unformatted space on the same disk. This does not mean a formatted partition with free space on it, it means unformatted, unallocated disk space. Extending is not supported on FAT/FAT32 partitions.
So if you do not need two separate partitions on one hard drive anymore, you must move the contents of the unneeded partition elsewhere (if you want to keep the files) and delete the partition. See instructions above for deleting a partition.
Again, extending a volume does not affect items already present on the volume you want to increase.
In Windows XP, you need to use the command-line DiskPart utility for this. In Windows Vista, 7 and 8, you can use the graphical and wizard-driven Disk Management console.
Click here to show or hide instructions on extending a partition in Windows XPUse keyboard shortcut Windows Key+R to open Run dialog (or open Start menu and click Run). Type "cmd" and click OK.
Type diskpart and press Enter key to launch the program.
Run list volume command to find the volume/partition you want to extend. In the example below it is Volume 2 with drive letter (the Ltr column) F. A volume that has "System" written in Info column is the partition where Windows is installed. Note the number of volume you want to resize.
Type select volume <volume number>, the digit being the number of volume you want to extend. In this case, the command is select volume 2.
As usual, press Enter key to launch the commands.
Type extend to add all available free space to the size of the partition. To specify an exact size for growth, type extend size=<number of megabytes to add>.
After the operation is complete, type exit and press Enter to quit DiskPart.
In the example below, list volume command was repeated to verify the volume size change.
Click here to show or hide instructions on extending a partition in Windows Vista, 7, 8 and 8.1
Right-click the NTFS volume or partition you want to make larger and click Extend Volume...:
Extend Volume Wizard opens. Click Next.
The Select the amount of space in MB box contains the largest available disk space for volume extension. This number is displayed in megabytes. You can decrease the size if you want to preserve some space for another volume/partition.
After setting your preference, click Next.
After the operation is complete, click Finish.
