The average IQ is 100 at every single age, from children to seniors, because IQ tests are age-normed to your own age group. 'Average IQ by age' charts that show rising or falling numbers are misleading, since the scoring is recalibrated for each age band.
The average IQ is 100 at every age, by design. IQ tests are age-normed, meaning your raw answers are compared only against people in your own age group before a score is assigned. This calibration forces the average to land at 100 for children, teens, adults, and seniors alike.
Those charts usually confuse raw ability with the normed score. A 7-year-old and a 30-year-old can both have an IQ of 100 despite hugely different raw knowledge, because each is scored against same-age peers. Charts that show IQ peaking at a certain age are mixing up underlying cognitive performance with the standardized 100-centered scale.
Your normed IQ stays fairly stable, but the underlying abilities shift with age. Fluid intelligence (on-the-spot reasoning and problem-solving) tends to peak in the early 20s and then declines slowly. Crystallized intelligence (vocabulary, facts, and accumulated knowledge) keeps rising into your 60s, often offsetting the fluid decline.
A child's IQ is never compared to adults; it is normed against same-age children. A 6-year-old scoring 115 is performing better than about 84% of other 6-year-olds, not 84% of grown-ups. This is why age-appropriate tests like the WISC exist separately from adult tests like the WAIS.
No, the average IQ for seniors is still 100 because their scores are normed against other seniors. While raw fluid-reasoning speed declines with age, crystallized knowledge stays strong or grows. Age-norming ensures a 75-year-old and a 25-year-old are each measured fairly within their own cohort.
| Age group | Average (normed) | Normal range | Note |
|---|---|---|---|
| Children (5-12) | 100 | 85-115 | Normed against same-age peers, not adults |
| Teens (13-17) | 100 | 85-115 | Fluid reasoning still developing toward its peak |
| Adults (18-29) | 100 | 85-115 | Fluid intelligence near its lifetime peak |
| Adults (30-49) | 100 | 85-115 | Fluid begins slow decline; crystallized keeps rising |
| Adults (50-69) | 100 | 85-115 | Crystallized knowledge often at its strongest |
| Seniors (70+) | 100 | 85-115 | Normed within cohort; vocabulary stays robust |