The Highest IQs in History: Estimated Scores of Great Minds

How Catharine Cox actually produced the numbers

Cox's method has a name: historiometry — applying quantitative measures to historical records. Her 1926 dissertation was the second volume in Lewis Terman's Genetic Studies of Genius series (Terman was a co-developer of the Stanford-Binet test). The team worked through roughly 1,500 biographies of 301 eminent people born between 1450 and 1850.

For each person, raters collected every anecdote about the subject's childhood and youth: the age they learned to read, when they first wrote poetry, how far ahead of classmates they were, what languages they mastered. They then asked a Stanford-Binet-style question — what IQ would a modern child need to hit these same milestones at these ages? — and assigned a score. They produced two estimates: one for development up to age 17 (labeled A1) and one for ages 17 to 26 (A2). Because biographical records are always incomplete, Cox applied a correction that nudged scores upward to counter regression toward the mean, reasoning that missing evidence made subjects look less precocious than they truly were.

Cox herself was careful in a way the pop lists are not. She graded the reliability of the evidence behind each estimate, and many figures rest on the weakest tiers of documentation. In her own words, the correction "indicates a point below which the true IQ probably did not fall" — a floor built on guesswork, not a precise reading.

Why these numbers are not comparable to modern scores

If a friend tells you they scored 190 on an IQ test, that means something very different from "Newton, 190." Four problems separate Cox's estimates from any modern result.

1. They are estimates of behavior, not test results. No one born in 1642 ever sat an IQ test. Cox measured how impressive the surviving stories were, which depends as much on record-keeping and fame as on ability.
2. The evidence is biased toward the famous and the documented. A child prodigy from a wealthy, literate family leaves a rich paper trail; an equally gifted child from a poor one leaves almost none. Cox's pool was self-selected for eminence, so the method cannot help but reward people who were already legendary.
3. Old childhood IQs inflate the numbers. Early IQ used a "ratio" formula (mental age divided by actual age, times 100), which can spit out enormous figures for a precocious young child. Modern tests abandoned that approach. Later scholars who re-corrected Cox's data using more conservative methods pulled the top scores down sharply — one widely used adjustment lists Newton nearer 168 and Goethe nearer 188, well below the 190–210 the pop lists still quote.
4. The scale itself has drifted. Average measured performance shifted across the 20th century (the Flynn effect), so a raw score from one era does not line up cleanly with another. Comparing a 1500s biography to a 2026 test result is comparing two different rulers.

How this is different from "highest IQ ever" debates

It is easy to blur two separate questions, so keep them apart. This article is about historical figures scored through historiometry — dead geniuses whose numbers were reconstructed from biographies decades or centuries after they lived. That is a different conversation from the modern "highest IQ ever recorded" debate, which involves living or recent people such as Marilyn vos Savant or William James Sidis, and revolves around disputed childhood test scores and unverifiable claims rather than biographical reconstruction.

Both share a common thread — the eye-catching numbers are softer than they look — but the reasons differ. Cox's figures are honest scholarly estimates of the long-dead; the record-holder debates are arguments over whether anyone was ever really tested at those heights at all.

Related

The Highest IQ Ever Recorded: Who Holds It, and Why It's Disputed

The highest IQ ever recorded is usually credited to names like Marilyn vos Savant or William Sidis, but the numbers (up to 300) are disputed and mostly unmeasurable.

The honest takeaway

Cox's study was a serious, pioneering piece of research, and it deserves respect for what it was: an early attempt to study genius with data. What it was not is a measurement of intelligence. Treat "Goethe, 210" the way you would treat a historian's careful guess about a medieval population — informative, defensible, and nowhere near a precise fact.

The more useful lesson is about the IQ scale itself. A real, modern test gives you a score with known reliability and a clear reference group. That is something no biography of Newton can offer, however brilliant its subject. If you are curious where you actually sit on that scale today, that is a question you can answer directly — with a real test rather than a reconstructed guess.

Related

Genius IQ Level: What Score Counts as Genius?

There is no official cutoff for genius, but scores of 140+ have traditionally been called genius or near-genius, and 130+ already ranks in the gifted top 2%.

FAQ

Q: Who has the highest IQ in history?

A: By the most commonly cited figures, Johann Wolfgang von Goethe, at an estimated IQ around 210. But this comes from Catharine Cox's 1926 historiometric study, which estimated childhood IQ from biographies rather than testing anyone. It is a scholarly guess, and different corrections of the same data rank the top spots differently.

Q: Did Newton, Leonardo, or Einstein ever take an IQ test?

A: No. Newton, Leonardo, and Einstein all lived before or largely outside standardized IQ testing, and there is no record of any of them sitting one. The numbers attached to them are later estimates — Cox-style historiometric guesses for the older figures, and popular back-calculations for the rest.

Q: Are Cox's estimated IQ numbers reliable?

A: Only loosely. Cox herself graded much of her evidence as weak, applied an upward correction to fill gaps, and used a childhood ratio method that inflates scores. Later researchers who re-analyzed her data produced substantially lower figures, so the exact numbers should be read as rough estimates, not measurements.

Q: Why do the highest historical IQ numbers vary so much between websites?

A: Because sites copy different versions of the same underlying data. Some quote Cox's raw estimates, others quote her regression-corrected figures, and still others apply later Flynn-effect adjustments that lower the top scores. Same study, different math — which is why Goethe can appear anywhere from 180 to 225.

References

• Cox, C. M. (1926). The Early Mental Traits of Three Hundred Geniuses — overview and legacy, Catharine Cox Miles, Wikipedia
• Cox's IQ Estimates of 301 Eminent Geniuses (with raw and corrected figures) — IQ Comparison Site
• Simonton, D. K. (2009). "Cox's 282 Geniuses Revisited" — Psychological Science

Last updated: July 13, 2026