How to Format a Flash Drive

by Ken Burnside

Flash drives have nearly replaced the floppy disk and optical drive as removable storage on computers. They're physically smaller, have a higher capacity and are vastly more convenient. When you get a flash drive from someone else and want to safely reuse it, or if you're going to give one of your flash drives to someone as a gift, you'll want to format it as a basic precaution.

Formatting the Drive in Windows

You can format a flash drive in Windows by clicking the "Start" button, clicking "Computer," right-clicking your flash drive (labeled as "Removable Disk" with a drive letter) and selecting "Format." The Format dialog box appears, where you can configure formatting options before clicking "Start" to format the flash drive.

Formatting Options

The Format dialog box in Windows enables you to configure the capacity (which allows you to select different partitions on the same drive so they can be formatted individually), file system and allocation unit size. You'll also have a space to rename the drive by giving it a volume label. A volume label is limited to 11 characters for FAT and FAT32 drives and 32 characters for exFAT and NTFS drives.

File System Choices

The file system is the set of rules that defines how an operating system accesses and displays data on the flash drive. The default file system on 64-bit versions of Windows is FAT32, and the default on 32-bit versions of Windows is FAT. FAT is limited to formatting drives of 4GB and smaller, while FAT32 can handle drives of up to 2 terabytes. FAT32 and FAT offer the widest compatibility with other operating systems and equipment, including Linux, MacOS and older versions of Windows. Another choice is NTFS, which can be made into a bootable drive for a Windows computer with a bit of extra work. NTFS reduces odds of data loss if a file becomes damaged, as well as giving better security over individual files, by allowing password-protection of directories and specifying read, write and executable access. The exFAT file system, which is a version of FAT32, can also reduce the risk of data loss with file corruption. The exFAT file system is supported in Windows XP with Service Pack 2 or later operating systems. A driver for exFAT is in every version of MacOS from version 10.6.5 (Snow Leopard) onward. Due to software patents, exFAT support on Linux is much less prevalent.

Allocation Unit Size

You can select a variety of allocation unit sizes when formatting a drive. The allocation unit size of a disk represents the smallest amount of disk surface that a file can use. This means that if your file allocation size is 4KB and you save a 1KB file, the file will consume 4KB on the disk. If you've ever wondered why your flash drive rated at 8GB only seems to show 7.6GB of storage space, this is why. The benefit to larger allocation unit size increments is they improve the speed at which data is read from the drive; in a nutshell, use larger file allocation units if you expect to use the drive for large multimedia files and use smaller sizes if you expect to use a lot of small files where read speed isn't as critical.

Quick Format and Full Format

The last choice to make is whether to select Quick Format. A quick format simply erases all the files on the hard drive and also erases the index file that allows their file names to be accessed. A full format does all of this and scans the flash drive for bad sectors, isolating them. For most flash drives, choosing full format is recommended because the extra time spent on a full format is trivial and flash drives frequently develop bad sectors as they age.

About the Author

Ken Burnside has been writing freelance since 1990, contributing to publications as diverse as "Pyramid" and "Training & Simulations Journal." A Microsoft MVP in Excel, he holds a Bachelor of Arts in English from the University of Alaska. He won the Origins Award for Attack Vector: Tactical, a board game about space combat.

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