Leonhard Euler's IQ: What the Evidence Supports

A record without a score

Euler died in St. Petersburg on 18 September 1783, 122 years before Alfred Binet and Théodore Simon published the first practical intelligence scale. No score exists. The usual fallback for historical figures is Catharine Cox's 1926 study, which assigned retrospective IQs to 301 eminent people born between 1450 and 1850. Euler, born in 1707, falls inside that window and still does not appear. Cox drew her subjects from the upper half of James McKeen Cattell's ranking of 1,000 eminent people and demanded detailed records of childhood and youth. Newton, Leibniz, Pascal and Descartes made her list. Euler did not.

So there is no scholarly number for him, and our Leonhard Euler profile does not invent one. For the mechanics of retrospective scoring, see how historical IQ estimates are made.

The circulating numbers, and why they fail

The online figures disagree with each other, which is the first warning sign. Parade gives Euler "estimated IQ scores that range from 180 to 200." A 2026 HistorySnob roundup puts him at 195–210. Neither cites a test, a rater or a method. A 30-point spread between two unsourced guesses is not a margin of error; it is the absence of data.

The figures also strain the scale they borrow. On a deviation scale with a standard deviation of 15, an IQ of 180 occurs in about one person in 21 million, and an IQ of 200 in about one in 76 billion, several times the world's population. No standard adult test reports scores in that range; the WAIS-IV stops at 160.

Memory and calculation: the documented feats

The anecdotes about Euler's mind are unusually specific. He memorized Virgil's Aeneid early in life, and in old age could still recite it and give the first and last sentence on each page of the edition he learned from. He knew the first hundred prime numbers and could give each of their powers up to the sixth.

The formal record is just as early. He entered the University of Basel at 14, in 1720, and completed a master's degree in philosophy in 1723. Johann Bernoulli, one of Europe's leading mathematicians, gave him free access every Saturday afternoon to work through the difficulties he had collected. He arrived at the St. Petersburg Academy in May 1727, aged 20, and in 1733 took over its senior chair of mathematics.

Output by the numbers

Euler's productivity can be counted, which makes it harder to exaggerate. The Eneström index lists 866 publications. He left more than 4,500 letters. His collected works, the Opera Omnia, have passed 80 volumes, and historians estimate he wrote a quarter to a third of all mathematical and scientific output of the 18th century.

• 1735: solved the Basel problem, proving that the sum of the reciprocals of the squares equals π²/6.
• 1735: presented his solution to the Seven Bridges of Königsberg, the founding problem of graph theory.
• 1741–1766: wrote more than 380 articles during 25 years at the Berlin Academy.
• Notation: introduced or popularized f(x), e, i, π and Σ, symbols every student still writes.

Blindness as a stress test

The strongest evidence of raw cognitive capacity is what happened when Euler lost his sight. In 1738 he became almost blind in his right eye. In 1766 a cataract was found in his left, and by 1771 he was essentially blind. His output rose. In 1775 he produced, on average, one mathematical paper a week, and roughly half his lifetime work dates from after 1766, worked out in his head and dictated to assistants.

That is working memory and mental arithmetic sustained at a level no timed test samples. When he died in 1783, Condorcet's eulogy compressed his life into one line: "il cessa de calculer et de vivre" — he ceased to calculate and to live.

Euler vs Gauss, Newton and Ramanujan

Comparisons by IQ number fail for a simple reason: the numbers are not real. Carl Friedrich Gauss is also missing from Cox, and the 250–300 range attached to him is even less plausible than Euler's figures. Isaac Newton is the one peer with a scholarly figure, Cox's corrected estimate of 190, and it rests on a thin biographical method. Srinivasa Ramanujan, whose 1913 letter led Hardy and Littlewood to ask whether he was "an Euler," has no estimate either.

Judged by record, Euler's distinction is range and volume; Gauss's is depth and finish. Laplace reportedly urged students to read Euler as the master of them all. Compare the two directly in Gauss vs Euler, or see the full mathematicians' IQ ranking.

What an IQ number cannot capture

An IQ score ranks performance on a short set of puzzles against a norm group. Euler's defining trait was sustained production over nearly six decades, across almost every branch of mathematics then known, under conditions that would have stopped most scholars: two moves between St. Petersburg and Berlin, the loss of his sight, and 13 children, of whom five survived childhood. No test measures stamina of that kind.

Our method here was simple. We checked for any recorded test, any Cox entry and any published historiometric estimate, found none, and relied instead on the MacTutor archive and the catalogued record of his works. We report no number because the evidence supports none. What it does support is a place among the most productive minds in the history of science.

Editorial standard: IQ figures for historical figures are retrospective estimates and are labeled as such; scores for living people appear only when the person disclosed them or a reputable outlet reported them. Corrections: contact the editors.