IQ Score by Age: What's Normal for Kids, Teens, and Adults?

One of the most misunderstood facts about IQ testing: a score of 100 always means the same thing regardless of age — it means you performed at the median for your age group. A 10-year-old with IQ 100 and a 45-year-old with IQ 100 are both exactly average for their peers.

This is because modern IQ tests use age-normed scoring: your raw performance is compared only to other people your age. Here's what that looks like across the lifespan.

How Age-Normed IQ Scoring Works

IQ tests are normed on large, representative population samples, broken into age bands (e.g., 16–17, 18–19, 20–24, 25–29, 30–34, and so on for adults; narrower bands for children; see IQ tests for adults for how the adult bands work). Your raw score — the number of questions you answered correctly, weighted by difficulty — is converted to a standardized score by comparing it to everyone else in your age band.

This means:

• A 12-year-old doesn't need to match adult performance to score 100
• A 70-year-old isn't penalized for having slower processing speed than a 25-year-old
• Everyone is always compared to their peers, not to the entire population

IQ Norms by Age Band

While the mean (100) and standard deviation (15) stay constant across ages by definition, different cognitive abilities peak and decline at different times:

Children: Ages 6–12

Children's IQ tests (like the WISC-5, Wechsler Intelligence Scale for Children) use narrower age bands — often as specific as 4-month intervals. Scores fluctuate more in childhood than adulthood. A child's IQ can change by 10–15 points between age 6 and 12 based on educational stimulation, nutrition, and development.

Average (IQ 90–110) is normal and expected. Scores above 130 at this age may indicate giftedness. Scores below 70 may indicate a need for additional educational support.

Teenagers: Ages 13–17

IQ begins to stabilize through adolescence. Fluid intelligence (pattern recognition, novel problem solving) keeps climbing through the teens. This is when many of the cognitive building blocks for adult performance are established. Academic performance in this age group is one of the strongest predictors of adult IQ scores.

Young Adults: Ages 18–30

This is the age range when fluid intelligence typically peaks. Young adults in their early-to-mid-20s perform best on novel problem-solving, working memory, and processing speed tasks. If you want your highest raw cognitive performance score, this is likely when you'd hit it.

Adults: Ages 30–54

A key finding from modern cognitive research: crystallized intelligence (vocabulary, accumulated knowledge, verbal reasoning) continues to grow well into the 40s and 50s, even as fluid intelligence begins a gradual decline. Adults in this range often outperform younger adults on verbal and quantitative tasks while being slightly slower on processing speed.

IQ scores in this range are highly stable — the most stable of any life stage. A 40-year-old's IQ score is a reliable predictor of their score 10 years later.

Adults 55+

Fluid intelligence declines more noticeably after 55, but age-normed IQ scores still remain stable — because 55-year-olds are compared to other 55-year-olds. What changes is the composition of abilities: processing speed slows, but verbal knowledge and reasoning often hold up well, especially in educated adults.

Physical health, cardiovascular fitness, cognitive engagement, and sleep quality all significantly influence cognitive performance in this age range. Healthy 70-year-olds often score comparably to less healthy 50-year-olds.

Average IQ by Age vs. Raw Ability by Age

Because every age band is scored against itself, the average IQ is 100 at every age — for 8-year-olds, 30-year-olds, and 75-year-olds alike. What does change with age is raw ability: how many problems a person can actually solve, and how fast. Intelligence research separates two broad kinds of ability, and they follow very different paths.

Fluid intelligence: peaks early, declines gradually

Fluid intelligence is reasoning about new problems — spotting patterns and working out rules without relying on prior knowledge. It rises steeply through childhood and adolescence, typically peaks in the mid-20s, and then declines slowly from the 30s onward; the decline becomes more noticeable after about 60 and varies a great deal between individuals. That is why timed matrix and pattern tasks tend to be easiest for young adults.

Crystallised intelligence: grows well into later life

Crystallised intelligence is accumulated knowledge and the skill of using it — vocabulary, general information, and verbal reasoning. It keeps growing through the 20s, 30s, 40s, and 50s, often peaks around 60 to 70 in healthy adults, and declines more slowly than fluid ability. It is heavily shaped by education and a stimulating environment, which is why many professionals and scholars do their best work in middle age despite slower raw processing speed.

What affects cognitive change over time

• Education: more years of formal education are consistently associated with better-maintained reasoning in later life
• Physical activity: aerobic exercise is one of the best-supported protectors of cognitive function in ageing
• Social and mental engagement: rich social networks and intellectually demanding activity support cognitive longevity
• Sleep: chronic sleep deprivation impairs performance at any age
• Nutrition: Mediterranean-style diets are associated with slower cognitive ageing

What Counts as a Good IQ at Different Ages?

Age Group	Average Range	Above Average	High/Gifted
6–12 (children)	85–115	116–125	126+
13–17 (teens)	85–115	116–125	126+
18–30 (young adults)	90–110	111–125	126+
30–54 (adults)	90–110	111–125	126+
55+ (older adults)	90–110	111–125	126+

Note: these ranges are the same across age groups by design — IQ is always relative to peers your age.

Key Takeaways

• IQ is always age-normed — 100 means "average for your age" at every stage of life
• Fluid intelligence (pattern recognition, processing speed) peaks in the early-to-mid 20s
• Crystallized intelligence (verbal knowledge, reasoning) continues growing into the 50s
• IQ scores are most stable in adulthood (30–65) and most variable in childhood
• Health, education, and lifestyle factors significantly influence cognitive performance at any age

Take our free-to-take IQ-style assessment — it uses modelled age-banded scoring rather than a generic adult table. These are not validated population norms, so read the percentile as indicative. See the percentile for any score →