External hard drives are a great way to easily expand the storage capacity of your computer. Just plug it in to a USB port and away you go. But sometimes you need to format the drive just so you can start fresh and get rid of all the files on the disk, or it came from the shop with an incorrect file system on it.
For example, it is NTFS but you want to use it on a Mac, or is HFS and you want to use it on Windows. Luckily, formatting an external drive is easy.
How to format an external hard drive – Windows 10
Open the Start Menu, type “Command Prompt” and select “Run as Administrator”. A black screen should pop up waiting for you to enter a command. Type in “diskpart” then press Enter. You’re now using DiskPart, which is ready for you to start manipulating disks.
The first step is to see what drives are hooked up to your computer. To do this we use the command “list disk”. Type it in and press Enter. You should see a list of the disks attached to the computer. Disk 0 is most likely the hard drive inside your computer. If that’s the only disk inside your computer, Disk 1 is your external hard drive.
An easy way to check if you’re playing around with the correct external hard drive (particularly if you have multiple), is to disconnect the drive you want to format, run DiskPart, list the disks and take note of the drives listed. Exit DiskPart (with the command “exit”), connect your drive back up, run DiskPart and list the disks again – the new drive is the one you just plugged in.
Now we need to tell DiskPart which hard drive we want to play around with. This is done with the “select disk” command. If your external hard drive is listed by DiskPart as disk 1, you would type “select disk 1”, press enter and be informed by DiskPart that “Disk 1 is now the selected disk”.
To totally wipe everything on the disk, all the partitions, all the disk signatures and any other bits and pieces that can introduce errors we will use the command “clean” (just type “clean” and press Enter). It’ll only take a few seconds. Now that the drive is wiped we need to tell Windows what to do with this raw slab of storage.
Type “select partition 1”, press Enter, then type “select partition 1”, press Enter, then type “active” then press Enter again. This sets up a new single partition filling the entire drive and by marking it as active, we are telling Windows that its allowed to use it for whatever it wants.
The next step is to give this new partition a file system – a method of telling Windows how it should store files on this drive. This is called “formatting” a drive. Type “format FS=NTFS label=External quick” and press Enter. This command creates an NTFS file system (the default file system type for Windows computers) and will give your external hard drive the rather unimaginative name “External”. Depending on the size of the drive this could take seconds or a few minutes.
The final step is to “mount” the drive by assigning it a drive letter. Type “assign letter=w” and press Enter. Now you have a W:\ drive all ready to go and store your data on.
How to Format an External Hard Drive – macOS
Open the Disk Utlity application, located in the /Applications/Utilities folder. Once open, choose View > Show All Devices to bring up a list of all the disks attached to your computer.
Click the disk you want to erase then click the Erase button in the menu bar. If you’re unsure which disk is your external drive, simply disconnect then re-connect the drive and the one that pops up after re-connecting is the one you want to erase.
After clicking the Erase button, you’re prompted to give the new disk a name (whatever you like is fine) select a partition map (select GUID) and a file system format.
You should select APFS here unless you plan on using the hard drive on older versions of macOS that don’t support it (i.e: prior to macOS 10.13 High Sierra). APFS (Encrypted) is recommended if this external hard drive will be moving around often with sensitive data.
By encrypting the drive, if anyone without the password plugs it in to a computer, they won’t be able to see what’s on it. The downside is that every time you connect the hard drive to a computer, you need to enter a password. If you would be upset if someone found your hard drive and poked around its contents, you should select APFS (Encrypted) for peace for mind.
After setting these options, click Erase. Your external hard drive has now been formatted.