How to Format USB on Mac

Last Updated: October 25, 2022

Most external hard drives and USB drives are compatible for use on Mac computers as long as you format the devices for use with Mac OS X. USB drives can be formatted on your Mac using the Disk Utility application.

Things You Should Know

Formatting a USB involves prepping the device to store information.
Most USBs are compatible with Mac if they are formatted beforehand.
When formatting USB drives on your Mac, you can use the Disk Utility application.

Steps

1
Connect your USB drive to your Mac computer.
2
Open the Applications folder and click on “Utilities.”

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3
Click on “Disk Utility.” The Disk Utility window will open and display on-screen.
4
Click on the name of your USB drive in the left window pane in Disk Utility.
5
Click on the “Erase” tab displayed at the top of the Disk Utility window.
6
Click on the dropdown menu next to “Format.”
7
Select “Mac OS Extended (Journaled),” or your preferred format type. The former option can help ensure that the USB drive is made fully compatible with your Mac, since most USB drives are preformatted for Windows computers by default.
8
Type a name for the USB drive in the “Name” field.
9
Click on the “Erase” button located at the bottom right corner of Disk Utility.
10
Click on “Erase” again when the confirmation dialog box displays on-screen. Your USB drive will now be formatted and ready for use on your Mac computer.^{[1]
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Community Q&A

Question

Will doing this make it ONLY compatible with a Mac? Currently I can use it anywhere but it's almost full and I can't seem to delete anything.

Friedolin Baum

Community Answer

Yes, if you choose "Mac OS Extended (Journaled)" in step 7, the USB drive will then only work with Mac computers.
Question

I need to format the USB with "FAT32 32KB." How can I do this?

Tenjingawa

Community Answer

First, open Disk Utility as shown in the article. Then select your USB from the list of disks on the left, and then click on "Info" on the top right. A new window will appear. Note down the "BSD device node" shown. After that, open Terminal (in the same Utilities folder). Then type the following commands into the window (without the quotes): "diskutil unmount /dev/[BSD device node]" "sudo newfs_msdos -F 32 -c 64 -v VOLUMEID /dev/[BSD device node]" (-F 32 means FAT32, while -c is "the number of sectors per cluster". FAT32 has a sector size of 512 bytes, so you need 64 of them to have 32KB per cluster; 512B×64=32768B=32KB) Then enter your password if required, and wait.