USB drive or flash drive not showing up on iPhone?

iPhones can use flash drives, USB drives and SSDs in the Files app, but only when a few things line up: the right format, enough power, a compatible port and adapter, and, for “phone drives”, an app that supports your model. Here’s what to check, how to remove a drive safely, and a cable-free option.

Check these first

Look in the Files app › Browse › Locations. Some phone drives are supported by their brand’s app only on Android; on iPhone they work through Files.
Format: iPhone reads exFAT, APFS, Mac OS Extended or FAT32, with a single partition. NTFS (common on Windows drives) can’t be written. Reformatting erases the drive, so copy its files off first.
Power: hard drives and some SSDs need more power than an iPhone gives. Use a powered USB hub, or Apple’s Lightning to USB 3 Camera Adapter with its charger plugged in.
USB 2 vs USB 3: some drives are only detected on a USB 3 port. Standard iPhone 15 and 16 models have USB 2 speed; Pro models have USB 3.
Unlock and allow: unlock the iPhone after plugging in, and check Settings › Face ID & Passcode › USB Accessories.
Firmware and case: update the drive’s firmware if its maker offers one, and remove a thick case if the plug doesn’t seat fully.

Remove a drive safely

The Files app has no eject button, so drives get unplugged mid-copy, and that’s how files and whole drives get corrupted. Wait until copying finishes, close any app using the drive, wait for its light to stop blinking, then unplug. If a drive was corrupted, run First Aid (Mac) or Check (Windows) and copy off what you can before reformatting.

Or skip the cable

A laptop, tablet or old phone can be your iPhone’s storage over Wi-Fi: no formats, adapters, power or unplugging to worry about. Open RoomDisk on both, scan the code, and send. Every file is checked when it lands.

Open roomdisk.com/app on the device that will keep the files and choose Use this device as the spare disk. It shows a QR code.
On the phone or computer with the files, scan that code. A phone’s Camera app works: tap the roomdisk.com link that pops up. RoomDisk opens and shows its own code.
On the spare disk, tap Scan reply and hold the phone’s screen up to its camera. (No camera there? Tap Share reply on the phone and open it on the disk device.)
Both screens say Connected. Choose files and send. Each file is checked when it lands.

Questions

Why does my drive work on my Mac but not my iPhone?

Usually the format (NTFS, or several partitions) or power. Drives that are fine on a computer may need a powered hub on a phone.

Why doesn’t my phone drive show up in its own app?

Some brands’ iPhone apps don’t support every drive. Try the Files app instead.

Try it with the two devices you have

Free to start. Nothing to install, no account.

Open RoomDisk