Average IQ by Age (2026 Update)
Official International IQ Test website (online since 2018)
Published by: International IQ Test
Last updated:
Below are the average IQ scores by age group, updated January 1, 2026. This report is based on data from
508493 people worldwide who took the same IQ test on this website in 2025
(mean: 100, SD: 15).
From childhood through young adulthood, the average IQ score increases and peaks between ages 18 and 29,
then gradually declines with age. The results closely match last year’s data (<1.2-point changes across
groups) and show the same overall pattern.
| Age group |
IQ |
Participants |
Previous year |
Difference |
| < 18 |
97.56 |
74196 |
98.04 |
-0.48 |
| 18-29 |
101.29 |
282869 |
101.36 |
-0.07 |
| 30-39 |
100.4 |
80233 |
100.19 |
+0.21 |
| 40-49 |
98.41 |
42773 |
97.82 |
+0.59 |
| 50-59 |
96.08 |
18557 |
95.32 |
+0.76 |
| 60-69 |
92.98 |
6950 |
92.02 |
+0.96 |
| > 70 |
91.89 |
2915 |
91.49 |
+0.4 |
FAQ
Why does average IQ peak between ages 18 and 29 and then decline with age?
Several factors likely contribute to this peak and gradual decline, including:
-
The prefrontal cortex—key for reasoning and decision-making—finishes maturing around ages 20–25.
This is discussed in the 2013 “Maturation of the adolescent brain” study.
-
Processing speed tends to slow with age. A 2010 neuroimaging study (Eckert et al., 2010)
describes slowed processing speed as “a hallmark of cognitive aging” and links it to structural changes in frontal and cerebellar brain networks.
-
Working memory and inhibitory control peak in early adulthood and may begin to decline around ages 30–40.
This is supported by a lifespan study of 350 participants (Ferguson et al., 2021),
which found continued improvement into the early 20s followed by gradual decreases throughout adulthood.
How were the participants selected?
All participants took the same IQ test on this website in 2025. To better reflect the global population,
the dataset was assembled using an approach similar to the one described in our
standardization report, including limits on the number
of participants per country based on each country’s population. We also applied filters to remove likely
repeat test-takers, potential bots, and other suspicious entries (e.g., checks based on IP address, pseudonym,
email address, etc.).
What is the official International IQ Test website?
international-iq-test.com
is the official website of the original "International IQ Test", online since 2018.
You can verify a website’s launch date using the Wayback Machine (archive.org).
This IQ test has been taken by over 16 million people
and has been standardized using psychometric criteria.