Does your IQ score change as you get older?

Your IQ score is defined relative to people your own age, so by design the average stays at 100 at every age. Your underlying abilities do shift over the lifespan, but the scaled score is always a comparison with your own age group.

What is the difference between fluid and crystallized intelligence?

Fluid intelligence is the ability to reason about and solve novel problems. Crystallized intelligence is accumulated knowledge and vocabulary. Research generally finds that fluid reasoning peaks earlier in life, while crystallized knowledge is well maintained and can keep growing into later adulthood.

At what age is intelligence at its peak?

There is no single peak age. Studies suggest different mental abilities peak at different times — some processing-speed tasks earlier in adulthood, vocabulary and knowledge much later. Intelligence is not one thing that rises and falls together.

Why does this test ask for my age?

Because IQ is age-normed. The same number of correct answers means something different at 14 than at 40, so your age is needed to compare you with the right peer group and produce a fair score.

Does IQ Change With Age? Fluid vs. Crystallized Intelligence

Your IQ score doesn't simply rise or fall with age, because it is always measured relative to people your own age — so the average stays at 100 throughout life. What does change is the mix of underlying abilities beneath that score: some kinds of reasoning tend to peak earlier, while accumulated knowledge keeps growing for decades. Here's what the research actually supports.

Why age-norming keeps the average at 100

IQ is a relative measure. Test makers compare your performance with a representative sample of people in your own age band, then scale the result so the group average is 100. This is called age-norming. Because the comparison is always within your age group, the average score is 100 at 12, at 30 and at 70 alike.

This is precisely why a fair test asks for your age. The same number of correct answers can correspond to a different IQ at different ages, so age is needed to place you against the right peers. We explain the scoring side of this in what a good IQ score means.

Fluid vs. crystallized intelligence

A useful framework, developed by Raymond Cattell and John Horn, splits general ability into two broad types:

Fluid intelligence — reasoning about new problems, spotting patterns and relationships without relying on prior knowledge. Non-verbal matrix tests lean heavily on this.
Crystallized intelligence — the store of knowledge, vocabulary and skills you have built up over a lifetime.

The broad pattern in the research is that fluid reasoning tends to be strongest in early adulthood and declines gradually thereafter, while crystallized knowledge is well preserved and can continue increasing into late middle age and beyond. The two move on different schedules — which is why "does intelligence decline with age?" has no simple yes-or-no answer.

There is no single peak age

Rather than one grand peak, studies point to different abilities peaking at different times. Hartshorne and Germine (2015) found, across a large sample, that some processing-speed and memory tasks tend to peak relatively early in adulthood, whereas vocabulary and accumulated knowledge can peak much later in life. In other words, a person can be past their peak on one ability while still improving on another.

A caution about method. Much of what we "know" about age and intelligence comes from cross-sectional studies that compare different people of different ages at one moment. Those comparisons can confuse genuine ageing with generational differences (the Flynn effect). Longitudinal studies that follow the same people over time often paint a gentler picture of decline. The exact figures depend heavily on the method used — which is why we avoid quoting precise age-by-age numbers here.

What this means for your result

If you take a reasoning test, your scaled IQ is a comparison with your own age group, not a raw measure of brainpower that inevitably falls each year. Abilities do shift across the lifespan, but the picture is nuanced: gradual changes in fluid reasoning alongside well-maintained or growing knowledge. The fairest way to see where you stand today is simply to take an age-normed test.