About 100 square millimeters.
The 3nm chip is about 100 square millimeters, which is comparable to 4nm and 5nm. The area size of the chip has little relationship with the level of the chip process, and is mainly limited by the use of space. At present, only mobile phones use such high-end processes in all electronic products, because the space size of mobile phones will not change much, so you can only increase the number of transistors to enhance the computing power, so the chip process will be higher and higher. The size of the mobile phone will not change much, so the space that can accommodate the chip will not change much, before it was 100 square millimeters, then the 3nm chip is also 100 square millimeters.