Does IQ change with age?
Updated 31 October 2026
An IQ score compares you with people your own age, so the average is 100 at every age. What changes over life are the abilities behind the score.
Average IQ by age
There’s no special “average IQ for a 15-year-old”: tests score you against people of the same age, so the average is always 100. A 10-year-old and a 50-year-old who both score 100 are both exactly average for their age.
How abilities change over life
On average, two kinds of ability follow different paths:
| Age | Reasoning with new problems | Knowledge and vocabulary |
|---|---|---|
| Childhood | Grows fast | Grows fast |
| Teens | Keeps growing | Keeps growing |
| 20s | Near its peak | Keeps growing |
| 30s to 50s | Slowly declines | Keeps growing |
| 60s and later | Declines faster | Stays fairly stable, then declines |
These are averages. Individual paths vary a lot, and health, education and an active life all play a part. More on the two kinds of ability in what is fluid intelligence?
Is IQ stable?
In children, scores can change quite a bit from year to year. From the teenage years on they become more stable: most people keep a similar position compared with their age group. Even so, the same person can score a few points differently on different days.
Quick answers
- What IQ is normal for a 13-year-old? The same as for anyone: 90 to 109 is average. See what is a good IQ score?
- Does IQ drop as you get older? Your score compared with your age group usually stays similar. Reasoning with new problems does slowly decline in later adulthood.
- From what age can you take UNIQUE? It’s designed for people aged 12 and over, and compares you with your age group. Its age norms are still provisional.
Find out your score
UNIQUE is a non-verbal IQ test: 64 matrices that adapt to your level. Taking it is free; you pay only to see your result.