You cannot take a real IQ test online. All the online tests are just for fun and tend to give everyone high scores, often ridiculously high - most are scams to steal personal information. If you want to know your real IQ score, ask your school or doctor to recommend a psychologist who can test you. It's not going to be free - in my area you would expect to pay about $300 for the test and scoring, and it takes several hours.
