A 28-nanometer chip is about 400 square millimeters.
A typical 14-nanometer cpu chip is about 160 square millimeters when unpackaged, which is about the size of a fingernail. The 28-nanometer chip is currently not suitable for mainstream computers, mainly used in vehicles, ships, aircraft and other electronic devices with low space requirements, and 400 square millimeters is about a little more than six centimeters long.
28 nanometers =1.10x 10^-6 inches. The conversion relationship is 1 inch = 2.5400 cm, 1 nanometer =1.00x 10^-7 cm, so 28 nanometers =28 x 1.00x 10^-7÷2.5400=1.10 x 10^-6 inches.