You often end up having to format your flash drive on Mac for one of the following reasons:

  1. Your USB drive has been corrupted somehow. 
  2. You want to use the flash drive on a specific OS and need to switch its format.
  3. You need a particular format to burn an ISO file on your pen drive

Whatever is your reason to want to format your flash drive on Mac, you will find below a step-by-step guide on how to do so from macOS. This tutorial uses the native tools offered in your current operating system.

If you’d rather use the command line, you can find a guide on how to format your flash drive on Mac using the Terminal HERE.

If you are a Windows 10 user, then click HERE for an article on how to format your pen drive. If you use Linux, you can find a handy guide HERE

What about the format?

If you are unsure of which file system to use, I recommend reading this article, which details each format you might encounter during the formatting process. For each one, you will also find a description, its use, its limitations, and operating system(s) compatibility.

Note for those looking to format their flash drive on Mac to burn a Windows 10 disc image.

You will have to take special precautions if you want to burn the ISO image of Windows 10 on your pen drive. This procedure requires a specific format to boot the OS. However, this format is almost always incompatible with the one needed for the OS itself. Instructions on how to burn the Windows 10 disc image on your pen drive can be found HERE for macOS and HERE for Linux.

The only exception to this rule is if you find a Windows 10 disk image under 4GB. In that case, you can format your pen drive as per this article’s guide, making sure to choose FAT32 as your file type.

Backup your files

Before formatting your flash drive on your Mac, make sure that its content (if any) has been backup beforehand. You will also need to do a backup if you only want to change your flash drive’s filetype. This procedure, even if technically not called “formatting,” will also erase your data. If you initially formatted your flash drive using Apple’s HFS+ format and now want to open your USB’s files on Windows, do a backup! You can’t switch the USB’s filetype from HFS+ to NTFS (the Windows proprietary format) and hope to be able to use its content on the other OS. You will have to backup, then switch to NTFS, then add the files back on the USB drive. Changing a filetype without any data loss is sometimes possible but beyond the scope of this article. 

How to format your flash drive on Mac (macOS High Sierra, macOS Mojave)


Insert the USB flash drive you want to format. If there is any content on it you want to keep, make sure to back it up first.

Open Disk Utility.

Look for your pen drive under the “External” menu located on the left. If your pen drive currently has a single partition, then your only option will be to select the whole USB stick. Otherwise, make sure to choose the full USB and not one of the partitions from the dropdown menu. Otherwise, you will only format this specific partition and not the whole drive.

Opening Disk Utility

Click on the “Erase” icon located on top. Alternatively, you can also click on “Erase” from the “Edit” menu or use the “Command – Up Arrow – E” keyboard shortcut.

You will be asked to choose the following three options: “Name,” “Format,” and “Scheme.”

Format your flash drive on Mac using Disk Utility

Name: Choose whatever name you want to give to your pen drive.

Format: By default, macOS uses the “Mac OS Extended (Journaled)” format. However, it also gives you the following alternative options: “Mac OS Extended (Case-sensitive, Journaled),” “MS-DOS (FAT)” or “ExFAT.” If you aren’t sure of which format to choose, you can find a detailed article on the subject HERE. I have also included a summary of each file type below:

Taking a look at the different formatting options in Disk Utility
  • Mac OS Extended (Journaled): The standard Mac OS format, this file type uses HFS+, a proprietary format developed by Apple Inc. The “journaling” refers to a technique that helps protect your pen drive’s integrity. Journaling protects by preventing disk inconsistency and proactively doing disk repair in case an error occurs during formatting. If you plan on using your pen drive on a Windows 10 operating system, do NOT choose this file type. Windows won’t be able to read or write the content of your USB flash drive.
  • Mac OS Extended (Case-sensitive, Journaled): Similar to the previous file type, this format is also HFS+. The only difference between these two formats is the presence of case sensitivity. This option is only useful if you plan on having two or more files within the same directory that will have the same name but different capitalization. With the “Mac OS Extended (Case-sensitive, Journaled)” option you can, for example, have “MyFile.txt” and “my file.txt” within the same folder. With the “Mac OS Extended (Journaled)” option, you cannot do that as both “MyFile.txt” and “myfile.txt” would be seen as the same file; you would need to either rename one or move it to a different folder. Once again, if you plan on using your pen drive on a Windows 10 operating system, do NOT choose this file type.
  • MS-DOS (FAT): An old school format, this file type is the equivalent of FAT32Compatible with all operating systems, including old ones, FAT32 is generally a great choice. It can be read and written on all versions of Windows, Mac, and Linux. It is also the de facto booting partition for Windows. There is only one caveat, however: its size limit. MS-DOS (FAT), aka FAT32, only accepts a maximum partition size of 2TB; and more importantly, it only allows files with a maximum size of 4GB or less.
  • ExFat: With virtually no file size limit, ExFAT is the best option for those looking for a cross-platform format that will work on both Mac and Windows. Note however that this file type is not user-friendly on older operating systems. Windows XP and Vista will require a patch update to read ExFAT, and this format is only compatible with Mac OS X 10.6.5 and later. If you want a pen drive that is compatible with all modern operating systems (Windows 7 and later, Mac OS X Snow Leopard onward), then choose FAT32.

Scheme: By default, the selected scheme is “Master Boot Record.” You can, however, choose to use “GUID Partition Map” or “Apple Partition Map” instead. Here are the things you need to consider when selecting a scheme:

Format your flash drive on Mac using Disk Utility
  • Do you plan on booting the disk image of a Windows or Linux operating system? If so, choose Master Boot Record (MBR). Note that with MBR, your external drive cannot be over 2TB.
  • Do you plan on using this pen drive to create a bootable Mac operating system? If so, choose Apple Partition Map.
  • Do you plan on using this pen drive on an older computer that has BIOS and not UEFI (machines manufactured in 2010 or earlier)? Or do you plan on using it on a Mac older than Mac OS X Tiger? Then use MBR.

For everything else, use GUID Partition Map (GPT). You could technically use the Master Boot Record scheme, but GPT is more modern and will eventually completely replace MBR as the default scheme.

(OPTIONAL) Alternatively, you can also take a look at the “Security Options…” before starting the formatting process. The Security Options are a replacement to the built-in encrypted format options. They allow you to prevent possible data recovery by obscuring the information you are deleting; it does so through encrypted formatting. If you are formatting a new pen drive, then this option does not apply to you, and you can skip directly to step #7. However, if you are formatting an external flash drive that contains sensitive data, then I recommend encryption. You have four options:

Disk Utility Security Options
Disk Utility Security Options
Disk Utility Security Options
Disk Utility Security Options
  • Option 1 – Fastest: This means no security measures are applied. Your drive will format very quickly, but data recovery apps might be able to recover your files.
  • Option 2 – Second option from the left: You will overwrite the disk twice. Once using random data, and a second time using zeros. This option is a good compromise for those looking for a somewhat quick formatting process while still getting some level of encryption in the process.
  • Option 3 – Third option from the left: You will overwrite the disk three times. Twice using random data, and a third time using known data. While slower than option 2, it provides heightened security.
  • Option 4 – The Most Secure: With this option selected, you will overwrite the seven times. Compliant with the US Department of Defence (DOD) standard for the secure erasing of data, it provides an excellent -if not overkill- encryption. Expect the formatting process to go at a snail’s pace with this level of security selected.

Remember: If you choose not to apply any security options, your data could potentially be recovered using disk recovery applications.

Once you have selected your format and scheme (and possibly security options), click “Erase.” Unless you chose a high-security level, the process should be quick.

Format your flash drive on Mac using Disk Utility

Mac will indicate that the erase process is complete. Click “Done.” Voilà!

Format your flash drive on Mac using Disk Utility

You can now safely eject the drive. To do so, click the eject icon located next to your USB key in the left menu. Make sure to eject the whole drive and not only your newly formatted primary partition. 

Can you use third-party software to format your flash drive on Mac?

Even though the Disk Utility is a fast and convenient way to format your flash drive on Mac, there are third-party applications capable of doing the same (and more). These apps can format your USB drive not only using the four formats seen above but also using others such as NTFS (for Windows), ext3 or ext4 (for Linux).

However, almost none of these programs are free. If you absolutely require NTFS read-and-write compatibility with Mac, then you might want to look at Paragon Software ( Note that I haven’t tested this software myself. If you wish to use NTFS to make your pen drive compatible with Windows, my suggestion is to simply use exFAT. It will allow you to do the same, without the limitations of a proprietary file type. As for ext3 or ext4, as their use is strictly for Linux, I recommend booting into a Linux distribution and formatting from there. You can easily do so from a virtual machine; if you’d like to know more about installing a Linux distro this way, head over HERE

Owner and content creator behind Geeky girl and blogger based in Montreal, Canada. Chocolate and nature lover (in that order). View all posts by Larryssa →

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