Originally Posted by CrystalSC
I have a 4S and I think it has a Micro. I believe the 5S uses Nano. I could be mistaken though. I'll double-check. Thanks!
I came from an iPhone 4S on AT&T to a Nexus 4 and then Nexus 5. The iPhone 4S uses a micro SIM, just like the Nexus 4 and 5. So you won't need an adapter. The nano SIM started with the iPhone 5.