Windows lets you reassign the letter your drive uses, but the process depends on whether it's an external drive or an internal one

Every storage device connected to your computer gets a letter — usually C for your main drive, then D, E, F and so on for others. You can change these letters yourself using Windows' built-in Disk Management tool. The steps are straightforward for external drives like USB sticks or external hard drives. Internal drives require a bit more caution, but the same tool handles both.

The reason you might want to change a drive letter: a new external drive grabbed a letter you wanted to keep for something else, or you're reorganizing how your drives appear in File Explorer. Whatever the reason, Windows makes this a reversible change — you can switch it back anytime.

Key Takeaways

  • Open Disk Management by right-clicking the Start button, selecting "Disk Management", or typing "diskmgmt.msc" into the search box.
  • Find your drive in the list, right-click the partition, and choose "Rename" to change its letter to any unused letter from D through Z.
  • External drives can be renamed at any time; internal drives should not be renamed while Windows is running from them.
  • If a letter is already taken, Windows will tell you — pick a different one from the available list.

Opening Disk Management on your computer

Disk Management is the Windows tool that controls drive letters. The fastest way to open it: right-click the Start button in the bottom left corner, then click "Disk Management" from the menu that appears. If you don't see it there, type "diskmgmt.msc" into the search box next to the Start button and press Enter.

You'll see a window split into two sections. The top half shows your physical drives. The bottom half shows the partitions on each drive — these are the sections that actually get letters. Find the drive or partition you want to rename in the bottom section.

Changing the letter for an external drive

External drives — USB sticks, external hard drives, SD cards — are the safest to rename because Windows doesn't depend on them to run. Right-click the partition you want to rename in the bottom section of Disk Management. A menu will appear. Click "Rename".

A dialog box will open showing the current letter. Delete it and type a new one. You can use any letter from D through Z that isn't already assigned to another drive. Click OK. Windows will change the letter immediately, and you'll see the new letter appear in File Explorer within seconds.

Changing the letter for an internal drive

Internal drives — the ones physically inside your computer — can be renamed the same way, but with one important rule: never rename the drive that Windows is currently running from. If you're using Windows right now, that's almost certainly your C drive. Renaming it while it's in use can cause Windows to stop working properly.

If you have a second internal drive and want to rename it, the process is identical to external drives: right-click the partition in Disk Management, click "Rename", type the new letter, and click OK. If you need to rename your C drive, you'll need to restart your computer from a different drive or use a Windows recovery environment — this is rare and usually not necessary.

What to do if the letter you want is already taken

Windows will show you an error if you try to assign a letter that's already in use. The solution is simple: pick a different letter. You can see which letters are already assigned by looking at the list in the "Rename" dialog — it shows you every letter currently in use on your system.

If you really want a specific letter and it's taken, you can rename the drive currently using it first. For example, if D is taken and you want D for a new external drive, rename the current D drive to something like E, then rename your external drive to D. This works because you're just moving letters around — there's no limit to how many times you can do it.

Undoing a drive letter change

If you change a drive letter and regret it, you can change it back the same way. Open Disk Management, right-click the partition, click "Rename", type the old letter, and click OK. There's no "undo" button, but since you control the process, you can always reverse it yourself.

The only exception: if you renamed a drive and then closed Disk Management, you might not remember what the old letter was. In that case, pick any unused letter and use it temporarily until you figure out what you want. You can rename it as many times as you need.

Why some drives won't let you change their letter

Occasionally you'll right-click a partition and the "Rename" option will be grayed out or missing. This usually means the partition is a system partition — one that Windows needs to boot. These are protected to prevent accidental damage. If this happens, you don't need to rename it. System partitions almost always use C anyway, and changing them requires advanced steps that aren't necessary for most people.

Another reason a partition might be locked: it's currently in use by a program. Close any open files or programs that are accessing that drive, then try again.

Frequently Asked Questions

Will changing a drive letter affect my files or programs?

No. Your files stay exactly where they are. Programs that are installed on that drive will continue to work because Windows updates the paths automatically. The only thing that changes is the letter you see in File Explorer.

Can I use the letter A or B?

Windows reserves A and B for floppy disk drives, which almost no computers have anymore. You can only assign letters C through Z. If you try to use A or B, Windows will reject it.

What happens if I unplug a drive without changing its letter back?

Nothing bad. The letter just sits unused until you plug the drive back in or assign it to something else. Windows doesn't care if a letter is temporarily unassigned.

Do I need to restart my computer after changing a drive letter?

No. External drives take effect immediately. Internal drives (except the one Windows is running from) also take effect right away. You'll see the new letter in File Explorer within a few seconds.

Can I change the letter of a drive that's currently being backed up?

You should wait until the backup finishes. If you change the letter while a backup is running, the backup program might lose track of the drive. It's safer to let the backup complete first, then rename the drive.