Your UDID is a unique identifier that Apple uses to associate a device to an iOS developer account so that developers can install and test their apps before releasing them.

Every iPhone, iPad and iPod Touch has a Unique Device Identifier (UDID), which is either a 40-character alphanumeric string (on iPhone X models and prior.) Or a 24 character identifier with a dash after the 8th digit, on iPhone XS and subsequent models) that is unique to each device.

On older models of iPhones like:

  • iPhone X
  • iPhone 8
  • iPhone 8 Plus
  • iPhone 7
  • iPhone 6s
  • And all models before these

Grabbing your UDID was simple.

Here is how you find your UDID number on iPhone X, iPhone 8, iPhone 8 Plus, and everyone released before them.

  1. Launch iTunes
    1. Make sure you check the box to turn off auto-syncing if you’re doing this for a co-worker.
  2. Under Devices, click on your device
  3. Next click on the ‘Serial Number’
  4. This will change the Serial Number into the UDID

This process has changed and is a bit more involved now for the iPhone XS family.

Retrieving the UDID on newer iPhone XS devices is still relatively simple, you just do not use iTunes.

Here is how to find your UDID on iPhone XR, iPhone XS Max, and iPhone XS:

  1. Connect your iPhone to your Mac
  2. Navigate to  -> About This Mac
  3. Click on System Report and select USB
  4. Click on iPhone
  5. Copy the value next to the Serial Number label
  6. Paste the value you just copied
  7. You then need to add a dash (-) after the 8th digit
    1. Sample Format = XXXXXXXX–XXXXXXXXXXXXXXXX
  8. This will be your UDID
Here are some screenshots that walk you thru the process.

Connect your iPhone to your Mac

Connect your iPhone to your Mac.

Navigate to  -> About This Mac

Navigate to  -> About This Mac

Click on System Report and select USB

Click on System Report and select USB

Click on iPhone, and copy the value next to the Serial Number label

Click on iPhone, and copy the value next to the Serial Number label

You then need to add a dash (-) after the 8th digit

Sample Format = XXXXXXXX–XXXXXXXXXXXXXXXX

This will be your UDID.