Guide: Formatting a USB Flash Drive for Mac & PC Compatibility
Last update: March 28, 2018
It's no surprise that PCs and Macs do not work well with each other, due to differences between the two operating systems (Windows vs macOS).
One main difference is file system. By default, Macs are with HFS+ (since 2017 there's new Apple File System, APFS, optimized for flash storage), while PCs are with NTFS.
If you have a USB drive, and you plan to use it on both a Mac and PC , things can get a bit tricky here. What do I mean?
If your disk was initially formatted to NTFS on a PC (or HFS+ on a Mac), most likely you'll suffer limitations, for example, the data on your drive can't be read or written on one of your computers.
Fortunately, there is a file system (actually two, I'll explain) that you can format your flash drive in order to be fully compatible with Mac and PC. In other words, you can access the drive and transfer data without any hassles.
That file system is — exFAT. Note that there is another file system called FAT32 that pretty much does the same thing but with one major flaw. See the table below for more info.
Major File System Comparison
Compatible with macOS?
Compatible with Windows?
Max. file size
Max. partition size
As you can see, exFAT is the only file system that works with all versions of Windows and macOS and does not have any max file-size or partition-size limits. Therefore, it's perfect for a USB flash drive or external disk especially you need to save files more than 4GB in size. You should go ahead and format your storage drive with exFAT instead of FAT32, assuming that all devices you want to use the drive support exFAT.
You may notice that in NTFS is marked "Partially" under the Compatible with macOS column. This is because an NTFS-based drive can be read by Macs but you can't write data to the drive.
Now that you've learned exFAT is the ideal file system to go. How to know what current file system your flash drive is with, and how to format it to exFAT?
Read on for step by step instructions...
How to Check a USB Drive's File System?
First of all, plug your flash drive into the USB port on your computer. Make sure your device can be detected and recognized. I'm here to use a 32GB Lexar USB key as an example.
If you are on a Mac...
Once the Lexar disk shows up on the desktop, right click on the drive icon and select "Get Info".
Alternatively (in case the disk does not show up on your desktop), open Finder, on the sidebar menu locate your USB drive under Devices, right click and select "Get Info".
In the new dialogue, pay attention to General > Format, where it says "MS-DOS (FAT32)". That means my Lexar disk is currently with the FAT32 file system.
If you are on a PC…
Go to This PC, under "Devices and drives", highlight the disk that represents your USB flash drive, right click and select Properties.
In the new Properties window, check General > File system and you'll see what type of file system your flash drive is currently with. Note: since I've formatted my Lexar drive on my Mac, now it shows exFAT.
How to Format Your USB Flash Drive to exFAT?
Important: make sure you have at least one backup of all the data stored on the device before you proceed. Because the process of reformatting a disk drive will very likely erase all content and make recovery impossible. See this USB drive recovery guide for more information.
Also, since I don't know whether you are on a PC or Mac to perform this operation. I'm here to break down this guide into two parts. The first part is for Mac users, the second part is for PC users (Windows 10 based). In no particular order.
Part 1: Formatting USB Drive on Mac
Please note: since OS X 10.11 El Capitan (the latest is 10.13 High Sierra), Apple made a few changes to Disk Utility (see details from this ComputerWorld post). The app now has a new user interface that looks slightly different on Yosemite or earlier OS X versions.
Step 1: Open Disk Utility. The quickest way is search on Spotlight and click the result under "TOP HIT". Alternatively, you can access it via Finder > Applications > Utilities > Disk Utility.
Step 2: Under "External" tab, highlight your flash drive. Note: right below your device name, it also shows information about the drive e.g. size, file system, etc. In my case, I can see it's a 32GB volume in MS-DOS(FAT) file system.
Step 3: Now click the "Erase" button at the top. In the new pop-up window, choose the format to be "ExFAT". You may also change the device name if you want. Then hit the "Erase" button to continue. Kind reminder: make sure you have backed up the data before you do this.
Step 4: Wait until the erasing process to complete. It should be very quick (only a few seconds to format my 32GB Lexar drive).
Step 5: This step is optional. I'm showing this to verify that the USB drive has been reformatted to the file system I wanted. I saved several files to the disk, and open Disk Utility again. And yes ... it's now with the exFAT file system.
Part 2: Formatting USB on a Windows PC
Please note: I'm here to use a Windows 10 based HP laptop to format my Lexar drive. If you are on an earlier operating system like Windows 7, XP, etc. The screenshots may look slightly different. For example, in Windows XP "My Computer" is equivalent to "This PC' on Windows 10.
Step 1: Locate your USB stick under "This PC", right click on it and select the "Format…" option.
Step 2: A new window pops up prompting options you need to select before starting. The only thing you have to check is under "File system", make sure you have chosen "exFAT". You may also rename the device drive under "Volume label". Then click the "Start" button to continue.
Step 3: You'll see this warning. Once again, make sure you've backed up all important data stored in the drive. Click "OK".
Step 4: It says "Format Complete", done!
Chances are that you may encounter some issues formatting a flash drive on a PC or the disk is malfunctioning. If so, the following articles may be of help to you:
Most of the external hard disks and flash drives are formatted for Microsoft Windows operating systems. That makes using the drive a bit troublesome on Mac machines. FAT32 is popular but the 4GB file-size limit makes it inconvenient, for instance when you want to make a bootable macOS Sierra USB drive which the system file takes about 8GB of storage space according to Apple.
Thankfully, exFAT — a strict upgrade over FAT32, is a file system optimized for USB flash drives. Like I said, if you want to use the device for both a PC and Mac, you should consider reformatting it to exFAT once you figure out the drive isn't with another file system.
Hope the above guide is helpful to you. Once again, as a kind warning: formatting a flash drive will likely erase all files and data stored in the device, it's important to ensure you have made at least one copy of the data before you get started.