There are a few things to keep in mind when you’re shopping for USB flash drives, and we also have some tips for using them.

Capacity: To decide on the capacity you need, first check the size of the folders or files you want to copy. Each USB drive in our guide has a stated capacity, but the usable storage will be slightly less than that, because the device’s firmware requires space.

Speed: USB standards are advancing all the time, and we recommend USB 3.0 as a minimum, though higher is better. While USB standards have different theoretical maximum speeds, it’s crucial to check the manufacturer’s stated read and write speeds for each drive. If you’re primarily transferring data, you’ll want to look for a drive with high write speeds. If you’re planning on launching software on a computer through the drive (like a video game), then you’ll want a model with high read speeds. Manufacturers will state average speeds, but most drives are much faster at transferring large files and tend to be far slower at transferring small files.

Compatibility: Many flash drives will work with any device with the relevant port, but check compatibility to avoid disappointment. If you want to use a drive with an Android device or one of the latest iPhone 15 range, it will require USB on-the-go (OTG) support. Most Android devices do support USB OTG. You will get a notification when you insert a flash drive with options that should include File Transfer. You can try the USB OTG Checker app to confirm support if you’re unsure. Apple’s earlier iPhones and iPads don’t support USB OTG, but you can install a companion app for drives, like SanDisk’s iXpand series.

Connectors: Most flash drives have USB-A connectors, but you can also get drives with USB-C, MicroUSB, and Lightning connectors. If you plan on using a flash drive with your smartphone and computer, snag one with both of the required types of connectors. You can also buy USB hubs with multiple ports or adapters, but pay close attention to the supported standard or it may limit your data transfer speeds. This Anker USB-A to USB-C adapter, for example, is USB 3.0.

Security: Remember that USB drives can cause security issues, particularly for businesses, and you should never plug in random drives you find lying around. If you plan to keep sensitive data on your flash drive, then consider biometric or passcode protection, and look into the level of encryption it offers. There are software services that offer encryption and allow you to password-protect your files on any USB flash drive.