IQ reference · Age chart · Score ranges

Average IQ by Age — Full Reference Chart

What counts as an average IQ at age 10? What about at 40? This reference article covers average IQ scores across all age groups, how cognitive ability changes through life, and how your score compares to the general population — with a complete data table and FAQ.

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How IQ scores work

IQ, or intelligence quotient, is a standardized score that places your raw test performance relative to a reference group — typically people of the same age. A score of 100 always means "exactly average for your age group" by design. Scores are usually distributed on a bell curve with a standard deviation of 15 points. That means roughly 68% of people score between 85 and 115, and about 95% score between 70 and 130.

This age-relative scoring is important: an 8-year-old and a 35-year-old can both have an IQ of 105, even though the 35-year-old would almost certainly outperform the child on an absolute reasoning task. The score tells you where you sit within your peer group, not how many problems you solved.

Average IQ score by age group

The ranges below are approximate population averages drawn from published cognitive-development research and large-scale IQ norming studies. Individual results vary widely. Scores are age-normalized on major assessments (WAIS, WISC, Stanford-Binet), so "average" is always anchored to 100 within each group.

Age group	Avg. IQ range	Cognitive notes
6–7	82–89	Early concrete reasoning; strong pattern and sequencing growth
8–9	90–96	Logical thinking develops; number reasoning improves rapidly
10–11	95–100	Approaching adult baseline; abstract reasoning begins to emerge
12–14	99–103	Formal operational stage; hypothesis-testing and deduction sharpen
15–17	100–105	Near-peak fluid intelligence; speed and working memory at high levels
18–24	100–108	Peak fluid intelligence window; reasoning speed typically highest
25–34	98–106	Crystallized intelligence rising; fluid speed stable or slightly declining
35–44	97–105	Vocabulary and knowledge compensate for minor speed decline
45–54	95–103	Processing speed decline begins; verbal and experiential reasoning strong
55–64	93–101	Fluid IQ dips further; accumulated knowledge and wisdom scores high
65–74	90–98	Crystallized skills remain; fluid tasks show measurable slowing
75+	84–93	Broader decline in processing speed; sustained verbal reasoning common

Source: Derived from WAIS-IV/WISC-V norming data and published developmental psychology research. Ranges are approximations and vary by test instrument and population sample.

IQ score classification table

This table shows how IQ scores are classified across the most widely used scoring systems. Percentile estimates apply to adults and are approximate.

IQ score range	Classification	Approx. percentile
Below 70	Extremely low	Below 2nd
70–79	Borderline	2nd–9th
80–89	Low average	9th–25th
90–109	Average	25th–73rd
110–119	High average	73rd–91st
120–129	Superior	91st–98th
130+	Very superior / Gifted	98th+

How IQ changes across a lifetime

Cognitive researchers distinguish between two broad types of intelligence that follow very different age trajectories. Fluid intelligence is your raw ability to reason about novel problems — to spot a pattern you have never seen before, hold multiple items in working memory, or make a logical deduction under time pressure. Fluid intelligence peaks roughly between the ages of 18 and 25 and then declines gradually over the following decades.

Crystallized intelligence is the accumulated knowledge, vocabulary, and practiced skills you have built up over a lifetime of experience and learning. It tends to grow well into middle age and remains relatively stable until well past 60. A seasoned professional who solves domain problems quickly is drawing on crystallized intelligence — they are not reasoning from scratch but retrieving and adapting existing knowledge.

The age patterns in the table above reflect this distinction. Young adults show high fluid IQ estimates because they are at peak raw reasoning speed. Older adults show a narrower but still significant range because crystallized ability compensates meaningfully for the decline in raw speed. A 55-year-old's IQ score can still be well above average even if their reaction time on a novel spatial puzzle is slower than a 22-year-old's.

The Flynn Effect: why average IQ has risen over time

One of the most surprising findings in intelligence research is that average raw IQ scores in many countries increased by roughly 3 points per decade throughout most of the 20th century. This trend — named after researcher James Flynn — means that if you took a 1950s IQ test using today's scoring norms, the average person from that era would score around 70. Conversely, if a typical person today were scored against 1950s norms, they would appear to be a borderline genius.

The most commonly cited explanations include improved early childhood nutrition, higher rates of formal education, greater exposure to abstract thinking through media and technology, smaller average family sizes allowing more individual cognitive stimulation, and reduced childhood exposure to environmental neurotoxins such as lead from paint and gasoline. The Flynn Effect has slowed and in some Scandinavian and developed nations has reversed slightly since the 1990s, which researchers attribute to diminishing returns on environmental improvements and possibly changes in educational curricula.

Internal links for further reading

If you want to see where your score falls on this chart, the fastest path is IQ Snap's free IQ test — 15 questions covering the core reasoning domains, live percentile feedback during the test, and an instant result. You can also try the 10 hardest IQ questions if you want to test the upper edge of the score range, or visit the IQ Snap homepage for a full overview of how the test works and what your score means.

FAQ

Average IQ by age — common questions

What is the average IQ score worldwide?

The global average IQ score is approximately 100 by design — IQ scales are standardized so that 100 represents the mean of the tested population. However, published national averages vary considerably due to differences in education quality, nutrition, healthcare access, and the specific versions of the tests used.

Does IQ change with age?

IQ scores are always interpreted relative to your age group, so an IQ of 100 means the same thing regardless of whether you are 10 or 50. However, the underlying cognitive abilities do change with age. Fluid intelligence — the ability to reason about new problems — typically peaks in the late teens or early twenties and gradually declines after that. Crystallized intelligence — knowledge and skills built up over time — tends to increase through midlife and remains stable well into older age.

At what age is IQ fully developed?

The brain's prefrontal cortex, which governs planning and abstract reasoning, is not fully mature until around age 25. However, IQ scores stabilize much earlier — by around age 16, most people's scores change very little relative to their peers. This means that while absolute cognitive ability continues to develop into the mid-20s, your relative position within your age cohort typically locks in during adolescence.

What is the Flynn Effect?

The Flynn Effect is the documented rise in average raw IQ scores over the 20th century — roughly 3 points per decade in many countries. The cause is debated: stronger candidates include better nutrition in early childhood, broader exposure to abstract thinking through education and media, smaller family sizes allowing more individual attention, and reduced exposure to environmental neurotoxins like lead. The effect has slowed or reversed in some high-income countries since the 1990s.

Is a score of 120 a good IQ?

A score of 120 places you in the 'superior' range, roughly in the top 9% of the population. That is a strong result by any standard. It is well above the average of 100 and above the 'high average' band (110–119). Whether it is 'good' depends entirely on your personal goals — for most purposes, including most professional and academic careers, it is more than sufficient.