This is way off topic, but:
Mensa does proper IQ tests. The problem is that there are (at least) three different scales, and that the average has gone up slightly over the years. The criteria for getting in is to be tested to be in the top 2 percent in any acceptable test.
I did the mensa specific test. I got a piece of paper saying how many questions I got right and what this meant in IQ score according to some scale. It didn't say my percentile, but I assume it's 98'th or better since I got in.
Short story: They measure IQ points, but since there are different scales, the definition of getting in is to be in the top 2 percentl.