How Do I Know Which iPhone Model I Have?

Find the model number on the back of iPhone

If you need to know frequency or replace the battery on your iPhone, you’re going to need to know which model it is.
You can find your iPhone model number by looking at the small text on the back of the iPhone.
This is a small number – like a serial number – printed on the reverse of the iPhone that starts with the letter “A”.

Identify your iPhone model -Apple