Average IQ by Age: What to Expect at Every Stage of Life
Last updated: June 1, 2025
Average IQ by Age: What to Expect at Every Stage of LifeLast updated: June 1, 2025
Does IQ change with age?
IQ scores are always age-standardized — you are compared to people in your own age group, not to the whole population. This means a healthy 65-year-old and a 25-year-old can both score 100, even though their raw cognitive abilities differ. What does change with age is the underlying raw performance on specific tasks: processing speed peaks in the mid-20s, while verbal knowledge and crystallized intelligence often improve into the 60s.
Average IQ Score by Age Group
The following table shows approximate average raw performance peaks for different cognitive abilities, based on normative data from the WAIS-IV (Wechsler, 2008).
| Age Group | Standardized IQ (Average) | Notes |
|---|---|---|
| 6–16 | 100 (normed) | Children's IQ measured with WISC, not WAIS |
| 17–19 | 100 | Processing speed near peak |
| 20–24 | 100 | Peak working memory and fluid intelligence |
| 25–34 | 100 | Crystallized intelligence growing |
| 35–44 | 100 | Verbal knowledge and reasoning peak |
| 45–54 | 100 | Slight declines in processing speed |
| 55–64 | 100 | Crystallized skills compensate |
| 65–74 | 100 | Age norms adjusted for cohort |
| 75+ | 100 | Greater individual variation |
All scores shown as 100 because IQ is standardized within each age group. Raw score differences are real but are normalized out of the final IQ number.
What cognitive abilities peak at different ages?
Different cognitive systems have different age trajectories:
| Cognitive Ability | Peak Age |
|---|---|
| Processing speed | ~20–24 |
| Working memory | ~20–30 |
| Fluid reasoning | ~25–35 |
| Verbal knowledge | ~45–65 |
| Crystallized intelligence | Peaks late, declines slowly |
| Wisdom / judgment | Increases with age |
Fluid intelligence (solving novel problems) tends to decline after the mid-30s. Crystallized intelligence (accumulated knowledge and vocabulary) often holds steady or improves into the 60s. This is why older adults often outperform younger ones on knowledge-based tasks while younger adults outperform on speed-based tasks.
Can children's IQ be measured reliably?
IQ can be measured reliably from around age 6 using specialized children's tests like the WISC-V (Wechsler Intelligence Scale for Children). Scores before age 6 are less stable and are usually expressed as developmental quotients rather than IQ scores. IQ scores in childhood are moderately predictive of adult scores, with predictive stability increasing significantly after age 10.
Does IQ decline with age?
Overall IQ scores tend to remain relatively stable across the adult lifespan, but specific abilities do change. Processing speed, working memory, and fluid reasoning show measurable declines from the 30s onward. However, crystallized abilities — vocabulary, general knowledge, expertise — often hold steady or grow. Lifestyle factors (physical exercise, mental activity, sleep, social engagement) are associated with slower cognitive decline.
Frequently Asked Questions
At what age is IQ fully developed?
General intelligence reaches its adult level by the late teens to early 20s for most people. However, the prefrontal cortex — important for judgment and planning — continues developing until around age 25.
Do IQ scores go down as you age?
Standardized IQ scores (compared to your age group) remain relatively stable throughout life. Raw processing speed does decline, but this is offset in the standardized score by age norms.
Is a child's IQ predictive of adult IQ?
Moderately yes. The correlation between childhood IQ (age 10) and adult IQ is approximately 0.70–0.80, meaning it is a reasonably good predictor but not a destiny.
Explore Cognitive Testing
Want to see how you perform? Try our free IQ-style test or the working memory test to explore different aspects of your cognition. For entertainment and educational purposes only.