IQ Score Estimator

IQ Score Estimator

Converts an IQ score to a population percentile and classification. IQ tests are standardized so that the average score is 100 and one standard deviation is 15 points (Wechsler scale).

IQ classification table (Wechsler scale)

Important disclaimers

• An IQ of 100 is exactly average: 50% of people score higher, 50% lower
• Only a certified psychologist administering a standardized test can provide a true IQ score
• Online IQ tests are not equivalent to clinical assessments
• IQ measures specific cognitive abilities, not general intelligence or life potential
• IQ scores are influenced by education, health, test anxiety, and cultural familiarity with the test format

The three IQ scales

• Wechsler: SD = 15, mean = 100. Most widely used (WAIS, WISC)
• Cattell: SD = 24, mean = 100. Used by some Mensa chapters
• Stanford-Binet: SD = 16, mean = 100. One of the oldest scales

The Flynn Effect and cultural bias

Two well-documented findings limit the interpretation of IQ scores across populations and time periods:

The Flynn Effect (Flynn 1984, 1987): IQ scores on standardized tests have risen by approximately 3 IQ points per decade in most industrialized countries since the early 20th century. This means a score of 100 today would have been ~130 on a test normed in the 1930s. The cause remains debated , candidates include better nutrition in early childhood, reduced lead exposure, longer formal education, and greater familiarity with abstract test formats. The effect is consistent enough that IQ tests must be re-normed every 10-20 years to maintain a mean of 100. A test normed 15+ years ago may overestimate current scores by 4-5 points.

Cultural loading: standardized IQ tests are normed on a specific population sample (typically US or UK for English-language tests). Vocabulary, general knowledge, and some abstract reasoning questions reflect cultural exposure patterns. Groups with less exposure to the test culture systematically score lower , not because of lower cognitive capacity, but because the norms are calibrated to a different cultural context. Nisbett et al. (2012) in American Psychologist reviewed the evidence: environmental factors, including quality of early education and nutrition, account for a substantial proportion of observed group differences in test scores. IQ scores are not fixed genetic traits.

What IQ tests do reliably predict within the same cultural context: academic achievement, some occupational outcomes, and certain aspects of information processing speed. What they do not measure: creativity, emotional intelligence, wisdom, practical problem-solving, or social competence.