Open the Settings app
Tap General
Tap About
Find the IMEI number in the list
Press and hold the IMEI to copy it
Dial *#06# on the Phone app
The IMEI will appear on the screen
Check the SIM tray on some iPhone models
Look on the back of older iPhone models
Check the original box label
Connect the iPhone to a Mac or PC
Open Finder on Mac or iTunes on Windows or older macOS
Select the iPhone
Find the IMEI in the device information
If you have a dual-SIM iPhone, check for IMEI and IMEI2 in Settings > General > About