IQ is not an absolute measure of intelligence, but rather a measure relative to the rest of the human population. IQ tests are normed so that IQ scores are distributed on a normal curve with mean 100 and standard deviation 15 (Wechsler) or 16 (Stanford-Binet), as shown in the graph below. Someone with IQ of 200 is at the 99.999999987th percentile. This means that (for the Weschler test) only about 1 out of 76 billion people, would score higher. Since the world population is less than 10 billion, the concept of IQ has no meaning at or above 200. At the time of this writing the world population is about 8 billion, so IQ as measured on Weschler has no meaning above 195. Similarly, the IQ as measured on the Stanford-Binet has no meaning above 202. The concept of IQ is a reasonable estimate of intelligence only in the range between 70 and 130, above that it is less clear how to compare IQ’s except to say that the people are highly intelligent.
