https://wccftech.com/can-you-use-your-iphone-13-with-an-iphone-12-case/

It has been some time since the iPhone 13 series came out, and to no one's surprise, the phones are excellent. Even though they pack minor changes in the overall design language, Apple has updated the hardware and made the phones better than ever. At first glance, you might think that the phones are nearly identical to their counterparts in the iPhone 12 lineup, especially when you look at the flat edges and edge-to-edge display. Still, there are some minor physical changes, which are prominent enough to ensure that your iPhone 12 cases will not fit your iPhone 12.

Both iPhone 13 and iPhone 13 Pro use the exact dimensions. The phone is 5.78 inches tall, 2.82 inches wide, and 0.30 inches thick.