How to format a USB drive on a Mac or Windows

Formatting a USB Drive entails a lot more than simply making your USB Drive compatible with your OS.

It’s a fairly simple process that shouldn’t take more than a few seconds. Whether you’re a macOS user or a Windows user, this article will help you!

Format Variations

Before getting into how you can format your USB Drive it’s important to know what the available options actually mean. As you follow the steps below you’ll notice a few formats most daily users aren’t familiar with.

FAT(16/32) – This stands for File Allocation Table, a format compatible with macOS, Windows, and even Linux. This format uses less disk space while also making the disk writing procedures run faster.

NTFS – This stands for New Technology File System and is not compatible with all operating systems. NTFS does give you more options for encryption and compresses large files.

ExFAT – The Extension File Allocation Table Format is compatible with later versions of macOS, Windows, and Linux systems. The ExFat format is the one to use if you need to store larger files across various platforms.

Now that we have a very basic understanding of your options, let’s get right into reviewing how you can make the appropriate changes.

How to format a USB drive on a Windows PC

Formatting a USB drive in Windows is normally very easy, here’s how it is done.

Step one

Type ‘This PC’ into the Cortana Search Bar. Click on the first option that appears.

Step two

Open the app and right-click on the USB drive you’d like to format.

You can also right-click the USB drive in the left-hand menu to access the settings.

Step three

Click on ‘Format.’

Step four

A pop-up window will appear and it is here you can make your formatting selections. Choose the options that best fit your needs and click ‘Start.’

Step five

A warning will appear letting you know that all information on the USB Drive will be erased. When ready, click ‘Ok.’

Wait for the process to complete then exit out of the window. Now, you can use your USB Drive how you’d like.

If you’re using an older version of Windows, you may need to access the Windows Explorer then follow similar steps.

How to format a USB drive on a Mac

Apple doesn’t make it quite as easy to format your USB Drive as Windows does. So, we’ll take you through two scenarios to get your Drive working properly.

The Disk Isn’t Readable

This is a really common error that occurs when you first insert your USB Drive. But don’t worry, we know how to fix it.

Step one

In the error message click on ‘Initialize.’ If nothing happens, head over to your Finder and click on ‘Applications’ on the left-hand side.

Step Two

From here, use the search bar in the upper right-hand corner to type ‘Disk Utility.’ Click on it.

Step three

Right-click your USB Drive (use Control+Click on a Macbook). Select ‘Erase.’ In the new pop-up window, change the format.

When you’re ready, click ‘Erase’ again. Let the process complete and your USB Drive will appear.

Format a Readable USB Drive

If you don’t have the issue described above, simply follow these steps:

Step one

To format a USB on a Mac, you can format your drive using Disk Utility.

You’ll find this tool in your Applications folder, within the Utilities subfolder – or simply search Spotlight to find it (press Cmd+Space, then type its name).

Step two

When Disk Utility opens you’ll see a list of drives in the left-hand pane, with the partitions on each one nested beneath each entry. To reformat your USB disk, click on its name in this pane, then switch to the Erase tab in the main interface (if it’s not already selected) and hit Erase to wipe the Drive just as we did above.

Choosing the Right Format

If you follow the instructions above then Windows will, by default, format your disk using Microsoft’s NTFS filesystem, while a Mac might suggest the Mac OS Extended filesystem.

These formats are sensible defaults because they support all the features of their respective operating systems, such as native compression and encryption. However, neither is suitable if you want to move files back and forth between Macs and PCs: OS X can read NTFS volumes, but it can’t write to them, while Windows in its default configuration can’t access HFS+ disks at all. There are free drivers available, but again these are limited to read-only access.

To use your USB disk on both Windows and OS X, therefore, you’ll need to use a different filesystem. You can choose this from the drop-down menu in Windows’ Format dialogue, or in the Erase pane of Disk Utility. In most cases we recommend you select Microsoft’s exFAT format: this will give you full read and write access in both Windows (Vista or later) and OS X (Snow Leopard 10.6.5 or later).

If you need compatibility with systems that are older than this, you’ll need to fall back to the ancient FAT32 format. This is supported by all versions of Windows and OS X (as well as Linux), but it has the drawback of not supporting individual files larger than 4GB – which can be a pain if you work with large video files or databases.

On a Mac, you can format any disk as FAT32 by simply choosing “MS-DOS (FAT)” from the dropdown menu in Disk Utility before you click Erase…. For historical reasons, Windows won’t offer FAT32 as an option if your disk is larger than 32GB, but you can format a disk of any size by opening a Command Prompt and typing format h: /fs:fat32 /q, where h: is the letter of your removable drive and the /q parameter specifies a quick format – assuming you don’t want to wait around for Windows to check each sector of the drive for errors.

How to format a USB drive: allocation unit size

As well as choosing a disk format, Windows also invites you to specify an “Allocation unit size”. Simply put, this determines the size of the chunks in which storage is allocated for your files: if you choose 4096 bytes (the NTFS default), every file that’s saved to that disk will be allocated space in multiples of 4KB.

Slicing up disk space in this way isn’t perfectly efficient. A file that’s only 1KB in size will still occupy 4KB of space, while a 5KB file will take up 8KB, and so on. In practice though, most of the files on your USB drive will probably be many megabytes in size, so the impact of wasting a few kilobytes here and there is negligible.

If you plan to save lots of small files to your disk then reducing the allocation unit size might be a good idea. However, this can have a negative impact on performance, especially if you’re using a mechanical disk drive. Splitting up a file into more chunks gives the drive controller more work to do, and makes it more likely that the data will end up fragmented into lots of blocks scattered about your disk, making it slower to access.

With a modern flash drive, it’s unlikely you’ll notice much difference either way, so it’s up to you whether you stick to the 4KB standard or pick a smaller allocation unit size.