Take a standardized, professionally administered IQ test
Use a test normed on a large, representative population
Compare your score to the test’s age-based norms
Report the resulting standard score as your IQ
Commonly used tests include WAIS, WISC, Stanford-Binet, and Raven’s Progressive Matrices
Avoid using online quizzes as a true IQ measure
Have the test administered and interpreted by a licensed psychologist
Re-test only when appropriate, since scores can vary with conditions and time