Professions tend to cluster around certain IQ ranges because cognitive demand acts as a natural filter. Jobs requiring complex analysis, abstract reasoning, or rapid learning draw people with higher average IQ - not because people with lower IQ cannot do them, but because they are less likely to pursue or complete the required training.
The figures below come from occupational testing research, primarily Linda Gottfredson's analyses of military AFQT data and Schmidt & Hunter's meta-analyses of job performance. They represent population averages, not cutoffs or requirements.
Average IQ by profession
| Profession | Average IQ Range |
|---|---|
| Professors and researchers | 130+ |
| Physicians and surgeons | 125-130 |
| Lawyers and attorneys | 120-125 |
| Engineers (all types) | 120-125 |
| Nurses and pharmacists | 110-115 |
| Teachers (K-12) | 105-115 |
| Sales managers | 110-115 |
| Skilled tradespeople | 100-110 |
| Clerical and administrative | 100-110 |
| Service industry workers | 95-105 |
These ranges carry wide variance. A mechanic specializing in complex diagnostics may score significantly higher than a junior attorney. The table reflects central tendencies, not individual ability.
Fluid vs. crystallized intelligence in careers
Fluid intelligence - the ability to reason through new problems without prior knowledge - matters most early in a career when you are learning quickly. It predicts training performance better than any other single factor (r=0.56, Schmidt & Hunter 1998).
Crystallized intelligence - accumulated knowledge and expertise - takes over as a predictor of performance once you have 5-10 years in a field. A surgeon with 20 years of experience relies more on pattern recognition built from thousands of cases than on raw reasoning speed.
Why high-complexity jobs cluster higher
The complexity threshold effect: for simple, routine jobs, IQ differences above about 110 produce minimal performance improvement. For highly complex jobs (law, medicine, research), there is no ceiling - higher IQ keeps predicting better performance. This is why the gap widens at the top.
Why IQ alone does not predict job success
IQ accounts for about 25% of variance in job performance for complex roles (Schmidt & Hunter, 1998). The remaining 75% comes from conscientiousness, domain knowledge, interpersonal skills, motivation, and experience. A brilliant but unreliable professional will consistently underperform a diligent average one.
Conscientiousness - being organized, reliable, and hardworking - is the personality trait that most consistently predicts job performance across all occupations. It is also largely independent of IQ, meaning the two traits combine multiplicatively rather than substituting for each other.
Find out your IQ score
35 questions · Stanford-Binet methodology · Free · Instant results
Take the Free IQ Test