What DFU actually is
Device Firmware Update mode loads the phone without starting iOS or the bootloader at all, which lets a computer write firmware to a device too broken for recovery mode to reach. It is the lowest-level state a user can put an iPhone into.
The tell is the screen: in recovery mode you see a cable and computer graphic, in DFU mode the screen stays completely black while the computer still detects the device. If you can see anything at all, you are not in DFU.
Try recovery mode first
DFU is not a better recovery mode, it is a more drastic one, and it always erases the device. Recovery mode can often reinstall iOS while keeping your data through its Update option.
Go to DFU only when recovery mode has failed or the phone will not enter it. Our recovery mode guide covers that first.
The sequence for iPhone 8 and later
Connect the iPhone to a computer and open Finder or the Apple Devices app. Press and release volume up. Press and release volume down. Press and hold the side button for about 10 seconds until the screen goes black. Then, still holding the side button, also hold volume down for about 5 seconds. Release the side button but keep holding volume down for another 10 seconds.
The screen must stay black throughout. If the Apple logo appears you held the side button too long; if the recovery screen appears you held volume down too long. Either way, start over.
Older models
iPhone 7 and 7 Plus: hold the side button and volume down for 8 seconds, then release the side button while continuing to hold volume down until the computer detects the device.
iPhone 6s and earlier: hold the side or top button and the Home button for 8 seconds, then release the side button while continuing to hold Home.
How to know it worked
The iPhone screen is entirely black — no logo, no cable graphic, no backlight — and Finder or the Apple Devices app says it has detected a device in recovery mode and must be restored before it can be used.
That combination is DFU. A black screen with no detection means the phone is simply off; try again.
It always erases, so plan for that
DFU restores are destructive by design: the device is rebuilt from firmware upward. Everything on it is lost, and only a backup made beforehand brings it back.
Our restore guide covers recovering your data, and our IPSW guide covers which versions can still be installed — Apple only signs a narrow window, so restoring to an older release is usually not possible.
Frequently Asked Questions
What is DFU mode on iPhone?
Device Firmware Update mode loads the phone without starting iOS at all, letting a computer write firmware to a device recovery mode cannot reach.
How do I know if my iPhone is in DFU mode?
The screen is completely black and the computer still detects the device. Any logo or cable graphic means you are not in DFU.
Does DFU mode erase everything?
Yes. A DFU restore rebuilds the device from firmware upward and is always destructive.
Should I use DFU or recovery mode?
Recovery mode first — it can reinstall iOS while keeping your data. Use DFU only when recovery mode fails.