Mark Gurman noted on X that Otterbox is already selling iPhone 18 Pro cases at Best Buy, despite the device not launching until mid-September. More notably, Otterbox's packaging claims the iPhone 18 Pro will fit iPhone 17 Pro cases and vice versa.

Gurman shared the packaging detail without confirming the sizing claims. However, rumors suggest the iPhone 18 Pro lineup will largely retain the same design as the iPhone 17 Pro models.

At least two leakers have claimed that the iPhone 18 Pro Max could be thicker and heavier than its predecessor, owing to its larger battery. This potential design change could affect case compatibility for that specific model.

The early availability of cases and cross-compatibility claims provide early insight into Apple's upcoming design decisions, though official confirmation won't come until the expected September launch.