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Jan 27, 2026·Average IQ & Demographics

What Is the Average IQ for a 12-Year-Old?

What is the average IQ for a 12-year-old? It is always 100. We explain how deviation IQ compares children to their specific age group.

Dr. Russell T. WarneChief Scientist
What Is the Average IQ for a 12-Year-Old?
The average IQ for a 12-year-old is 100, which is the same as the average for any other age. This answer surprises many people, because it seems like a 12-year-old should be less intelligent than an adult--and more intelligent than a kindergartener. Yet all of these groups have an average IQ of 100. But this fact reflects how IQ tests are scored. Modern intelligence tests compare examinees to others in their own age group, not to the general population. This means that a 12-year-old who performs exactly as well as the typical 12-year-old receives a score of 100, regardless of how that performance compares to adults or younger children.

How Are IQ Scores Calculated for Children?

Modern IQ tests use what psychologists call a deviation IQ. Test creators administer the assessment to a large, representative norm sample at each age level to establish average performance. An examinee's raw score is then compared to others in their age bracket and converted to a standardized scale with a mean of 100 and a standard deviation of 15.

This approach replaced the older "quotient IQ" method, which calculated IQ by dividing mental age by chronological age and multiplying by 100. Under that system, a 12-year-old performing like a typical 15-year-old would receive an IQ of 125 (15 ÷ 12 × 100). This produced inconsistent results across ages and broke down entirely for adults. The deviation IQ solves these issues by making scores directly comparable across the lifespan; a given IQ quantifies a person’s test performance relative to their age peers, whether the examinee is 8, 12, 25, or 60.

What Should a 12-Year-Old's IQ Be?

There is no IQ that a 12-year-old "should" have. Most children fall somewhere in the average range, with fewer at the extremes. About 68% of 12-year-olds score between 85 and 115, roughly 95% score between 70 and 130, and only about 2% score above 130, with another 2% scoring below 70.

A 12-year-old with an IQ of 95 is perfectly normal, as is one with an IQ of 105. Parents who expect their child to score significantly above 100 often misunderstand what "average" means. It simply describes the majority of children, not a minimum acceptable standard.

Does IQ Change During Childhood?

IQ scores show increasing stability as children age. A comprehensive meta-analysis of 205 longitudinal studies found that scores reach high levels by adolescence. By age 12, scores correlate strongly with those obtained years later, though some individual fluctuations still occur.

This stability does not mean IQ is fixed. Preschool scores are only moderately predictive of later performance, with stability increasing substantially through the school years. Environmental factors, particularly education, continue to affect cognitive development throughout childhood. What stabilizes is a child's relative standing compared to peers, not absolute cognitive capabilities.

The brain itself continues developing well past age 12. Neuroscience research shows that gray matter volume in the frontal lobes peaks around age 11-12 in girls and 12-13 in boys, with continued development of white matter connections through adolescence supporting the emergence of abstract reasoning abilities.

Why Do People Ask About "Average IQ by Age"?

People sometimes assume that IQ increases with age, or that a normal 12-year-old should have a higher IQ than a normal 8-year-old. However, with deviation IQs, the average is always 100 at every age because scoring is calibrated separately for each age group. A 12-year-old with an IQ of 100 has cognitive abilities typical for a 12-year-old; an 8-year-old with an IQ of 100 has abilities typical for an 8-year-old. The older child obviously knows more and can solve harder problems in absolute terms, but both perform at the average level relative to their peers.

What Do Different IQ Scores Mean for a 12-Year-Old?

Score interpretation remains consistent across ages. A score of 130 or above indicates very high cognitive ability, placing the child in approximately the top 2% of same-age peers. In fact, some gifted programs use this threshold. Scores between 115 and 129 indicate above-average ability, while 85 to 115 represent the average range that includes about two-thirds of all 12-year-olds. Scores between 70 and 85 indicate below-average ability, and a score below 70 (combined with limitations in adaptive functioning), may indicate intellectual disability.

Are IQ Tests Accurate for 12-Year-Olds?

Professionally developed IQ tests produce reliable scores for children aged 12. The same meta-analysis indicates that by this age, test-retest correlations exceed .70 even over intervals of several years. The major individually administered tests, including the Wechsler Intelligence Scale for Children (WISC) and the Stanford-Binet, have extensive research supporting their use with this age group.

Any single test administration captures performance at one moment in time. Factors like fatigue, anxiety, or illness can temporarily depress scores. For important decisions like eligibility for gifted programs or special education services, IQ scores should be considered alongside academic performance, teacher observations, and developmental history.

Where Can a 12-Year-Old Take an IQ Test?

The most common settings for childhood IQ testing are schools and clinical practices. School psychologists administer tests as part of evaluations for gifted programs or learning disability assessments, while private psychologists conduct comprehensive cognitive evaluations.

Currently, no professionally developed online IQ tests exist for children. The Reasoning and Intelligence Online Test (RIOT), created by Dr. Russell T. Warne with over 15 years of experience in intelligence research, is designed for adults (ages 18 and older) and meets rigorous standards established by the American Psychological Association, American Educational Research Association, and National Council on Measurement in Education. Parents interested in their child's cognitive abilities should consult a qualified psychologist who can administer an age-appropriate test and interpret results in context.

Watch “The Hidden Problem in Every Classroom: Why Teaching by Age Doesn’t Work” with Karen Rambo-Hernandez on the Riot IQ YouTube channel to understand why age-based averages can be misleading.
Author
Dr. Russell T. WarneChief Scientist

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