— Famous people & IQ
Thomas Jefferson IQ: 150 (estimated)
Thomas Jefferson's IQ is estimated at 150. This is a widely-cited estimate based on Thomas Jefferson's body of work and historical accounts — not a verified, administered psychometric test score. An IQ of 150 would place a person in the top 0.04% of the population (roughly 1 in 2,331).
Important note: Thomas Jefferson's IQ figure of 150 is an estimate. Most published celebrity IQ figures circulate without clinical sourcing. Treat the number as a defensible estimate, not a verified measurement.
Where the 150 estimate comes from
→Pause. Find out YOUR IQ before you keep reading.Catharine Cox's 1926 study The Early Mental Traits of Three Hundred Geniuses estimated childhood IQs for historical figures based on biographical evidence of precocity — age of first reading, age of first publication, mastery of subjects ahead of peers, and so on. Cox's method has been criticized for systematic upward bias but remains the most-cited source for pre-modern figures.
What the score implies — and what it doesn't
→Curious how YOU score? 20-min calibrated test.An IQ of 150 is in the Profoundly Gifted range — top 0.13% or so. Capable of mastering arbitrary abstract subjects with comparatively little instruction.
Thomas Jefferson's achievements in Statesman reflect more than raw IQ. The pattern across high-achieving figures is that cognitive ability gets you into the game; the variables that determine outcomes from there are conscientiousness, sustained focus, time-on-task, mentorship, environment, and a tolerance for the social isolation that often accompanies deep specialized work.
Comparison with peers in Statesman
→The numbers above? Find out where YOU land.| Person | Est. IQ | Note |
|---|---|---|
| Benjamin Franklin | 160 | Cox estimate |
| Thomas Jefferson | 150 | Cox estimate |
The limits of celebrity IQ estimates
→Knowing about IQ ≠ knowing yours. Take the test.- Historiometric estimates like Cox's are biographical inference, not measurement. Catharine Cox herself rated the reliability as "I" through "IV"; many figures are rated "III" or "IV" — weakest evidence.
- Childhood ratio-IQs (mental age / chronological age × 100) systematically inflate scores compared to modern deviation IQ. A 1900-era child labeled "IQ 200" would likely test 140-160 on a modern WAIS.
- Self-reported figures from public figures are essentially never independently verifiable.
- Achievement is not pure intelligence. The correlation between extreme achievement and pure IQ peaks around 130-140; above that, conscientiousness and circumstance dominate the variance.
Frequently asked
→Stop reading. Start testing →What is Thomas Jefferson's IQ?
Thomas Jefferson's IQ is widely estimated at 150, based on cox estimate. This is an estimate, not a clinically measured score.
Did Thomas Jefferson actually take an IQ test?
Likely not a formal modern IQ assessment. Celebrity IQ figures are usually estimates from secondary sources rather than verified clinical results.
How accurate is the IQ 150 figure?
Treat it as a defensible upper-end estimate within ±10-15 points. Famous-person IQ estimates carry substantial uncertainty and methodological bias.
Other figures in Statesman
→Pause. Find out YOUR IQ before you keep reading.Frequently asked about Thomas Jefferson's IQ
What was Thomas Jefferson's IQ?
Thomas Jefferson's IQ is estimated at 150, though this is a retrospective estimate based on their work and accomplishments rather than a verified test result.
Did Thomas Jefferson actually take an IQ test?
There is no reliable public record of Thomas Jefferson taking a standardized adult IQ test with a verified score. The figure of 150 is an estimate that circulates in popular media.
How rare is an IQ of 150?
An IQ of 150 occurs in roughly 1 in 2,331 people — the top 0.04% of the population on a standard deviation IQ scale (SD 15).
Is Thomas Jefferson's IQ score reliable?
Treat it as suggestive, not definitive. Famous-person IQ figures are often extrapolated from achievements, childhood ratio-IQ tests, or unsourced media claims, none of which are directly comparable to a modern administered adult IQ test.
Related reading
→Curious how YOU score? 20-min calibrated test.Sources: Cox, C. M. (1926), The Early Mental Traits of Three Hundred Geniuses; Simonton, D. K. (1994), Greatness: Who Makes History and Why; Eysenck, H. J. (1995), Genius: The Natural History of Creativity.
Find out your own IQ →