The area of an 8-inch plate is about 324. 13 cm2 or 557.6438+0 1 cm2. The size of the plate refers to the length of the diameter, and the radius = half of the diameter. If it is inches, then 8 inches =8x2.54=20.32cm, and the radius =10.16cm; If it is a city inch, then 8 inches =8x3.33=26.64cm, and the radius = 13.32.