Rumours say it could go sub 8mm.
The current iPhone 4S has a depth of 9.3mm but, according to Apple Insider, Apple will trim the fat on its next device using new touch panel tech.
It reckons a thinner battery and metal back will provide a final depth of 7.9mm – with no reduction in responsiveness.
Apple is expected to cut the size of the iPhone 5 in order to keep up with rival devices. Meanwhile, Samsung is expected to unveil a 7mm-thick Galaxy S III on May 3rd.