What Size USB Flash Drive Do I Need?

The size, speed and security needs of a USB flash drive depend on usage

USB drive
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The diversity of options in the USB flash drive market reflects the diversity of use cases that people factor into their buying decisions. It's not always the case that buying the biggest drive makes the most sense.

USB Flash Drive Considerations

The capacities of USB flash drives range from 2 gigabytes to 1 terabyte. Although the drives are affordable options for expanding storage capabilities, the price increases with the size. When you are shopping for a flash drive, you'll also be interested in transfers speed — whether the USB flash drive is USB 2.0 or 3.0 — and security.

Estimating Storage Space Needs

There's no simple formula for estimating your storage needs. The number of photos or songs that fits on a USB flash drive varies widely because of the type of media you use and the size and quality of each file. If each of your photos is 6 megapixels in size, you can fit 1,000 on a 2 GB drive, 8,000 on a 16 GB drive and 128,000 on a 256 GB drive. However as the size increases, the number of photos that fit decreases. If you work with high-resolution photos that average 24 MP, you'll only be able to put 250 on the small 2 GB flash drive and 32,000 on the 256 GB drive.

The same problem exists when trying to estimate the size of music and video. If you place all the files you want to transfer to a USB flash drive in one folder, you can get the size of the folder and that tells you how much space you need to move that one folder. If you shoot HD video, don't bother with any drive at the small end of the size scale. A 16 GB flash drive holds only one minute of HD video, while a 256 GB drive holds just 224 minutes.

By contrast, Word documents and Excel spreadsheets take up little space. If you are a student transferring these types of files between computers, a 2 GB drive is all you need. 

The Difference Between USB 2.0 and USB 3.0

Whether you choose a USB 2.0 or USB 3.0 depends in part on the device you are transferring from and the port you use. Confirm which speed your computer supports before buying a USB drive. If your equipment supports USB 3.0, buy that speed drive. Its transfer rate is 10 times faster than the speed of a USB 2.0 drive. 

Relative USB Speeds

Although the actual throughput performance of a USB device varies based on your computer's settings, in general, the theoretical maximum speed of a USB 2.0 device is 480 MB per second whereas USB 3.0 is 4.8 GB/s. In context, that means a 16 GB file, like a digital-video project, will transfer in less than a minute using USB 3.0 whereas it'll take nearly 9 minutes to transfer using the older standard.

About Security

Depending on your usage, you may want to buy a secure USB flash drive. This extra capability may not be necessary if you are just transferring a few non-confidential files from one home computer to another, but if you are using the drive with many computers or are archiving important or proprietary data on the drives, you'll need to protect the privacy of the device.

Potential security risks with USB drives include:

  • Their small size may cause them to be lost or overlooked.
  • They are hard to track physically. Some companies ban their use for this reason.
  • They can transfer malware from one computer to another and have done so frequently.

Nothing can be done about the small size of the thumb drive without forfeiting its portability, but software encryption — on Windows and Mac computers and from security companies — and hardware encryption on the USB drives themselves are help prevent malware transfer and unauthorized access.

At a minimum, you can configure a non-secure USB drive using BootLocker, Microsoft's disk-encryption tool, if you're running a Professional or Enterprise version of Windows 10. Alternatively, consider installing a program like TrueCrypt to offer on-the-fly encryption of removable media.