Highest IQ Ever Recorded: The Smartest People in History

Who has the highest IQ in the world? It's one of the most searched questions about intelligence. The answer is complicated — IQ scores above 160 are extremely difficult to measure reliably, and many historical claims are disputed. Here's what we actually know about the highest IQ scores ever documented.

The 15 Highest Recorded IQ Scores

Why Extreme IQ Scores Are Controversial

Most psychologists are skeptical of IQ scores above 160 for several important reasons:

• Test ceiling effects — Standard tests like the WAIS max out around 160. Scores above this require specialized high-range tests with limited validation.
• Statistical unreliability — IQ follows a normal distribution. At the extremes, tiny measurement errors translate into enormous score differences. The difference between "160" and "200" may not be meaningful.
• Childhood vs adult scores — Many extreme scores (Tao, Kim, Hirata) were obtained in childhood. The ratio method (mental age / chronological age × 100) inflates scores for precocious children. A 7-year-old performing at a 14-year-old's level gets a 200, but this doesn't mean adult IQ is 200.
• Historical estimates are guesses — Newton, da Vinci, and Goethe never took IQ tests. Their "scores" are researcher estimates based on achievements, which is inherently speculative.

William James Sidis: The Controversial #1

William James Sidis (1898-1944) is often cited as having the highest IQ ever — estimated between 250 and 300. Sidis was a spectacular child prodigy: he was reading at 18 months, gave a lecture at Harvard at age 11, and reportedly spoke over 25 languages. However, his adult life was unremarkable by genius standards — he worked clerical jobs and lived in relative obscurity until his death at 46.

The 250-300 estimate is highly disputed. It's based on the ratio method applied to his childhood precocity, which most modern psychologists consider invalid for producing accurate adult IQ scores. Sidis' story is often used to illustrate that extreme childhood IQ doesn't guarantee adult achievement, and that social and emotional factors matter enormously.

Terence Tao: The Living Genius

Terence Tao, born 1975, is widely considered the most intelligent living person by conventional measures. He scored 220-230 on IQ tests as a child, began university-level mathematics at age 9, earned his PhD at 21, and won the Fields Medal (mathematics' equivalent of the Nobel Prize) at 31. Unlike many child prodigies, Tao has sustained his intellectual output into adulthood, making contributions across multiple areas of mathematics.

Tao's case is significant because his childhood promise was fully realized in adult achievement — a rarity among extremely high-IQ individuals. He is a professor at UCLA and has published over 300 research papers spanning diverse mathematical fields.

What Is the Realistic Maximum Human IQ?

Most intelligence researchers believe the realistic measurable maximum for human IQ is somewhere around 170-190 on modern deviation-based tests. Claims above 200 are generally considered artifacts of outdated ratio-based scoring or unreliable high-range tests rather than genuine measurements. The important point is that above approximately 145-150, additional IQ points become less meaningful — the difference between a 150 and a 180 in real-world capability is far less than the difference between a 100 and a 130.

Highest IQ by Category

Highest IQ Among Scientists

Isaac Newton (190-200 estimated) and Marie Curie (180-200 estimated) are typically ranked as the most cognitively gifted scientists in history. Among living scientists, Terence Tao leads, with physicist Edward Witten and computer scientist Donald Knuth also frequently mentioned.

Highest IQ Among World Leaders

Among US presidents, John Quincy Adams (estimated 175), Thomas Jefferson (estimated 160), and John F. Kennedy (estimated 150-160) are typically ranked highest. Among global leaders, Benjamin Franklin (estimated 160) and Winston Churchill (estimated 150) are frequently cited.

Highest IQ Among Athletes

While athletes are rarely tested, those known for strategic thinking score above average. Cristiano Ronaldo is estimated at 105-115. Chess grandmaster Magnus Carlsen has been estimated at 190, though chess-specific intelligence doesn't directly translate to general IQ.

Frequently Asked Questions

What is the highest IQ ever recorded?

William James Sidis is estimated at 250-300 (disputed). Terence Tao tested at 220-230 as a child. Marilyn vos Savant was listed at 228. Most psychologists consider scores above 160 unreliable.

Who has the highest IQ in the world right now?

Terence Tao (220-230) is most commonly cited. Christopher Hirata (225) and Kim Ung-Yong (210) are also mentioned. Adult verification of such extreme scores is extremely difficult.

Is an IQ of 200 possible?

Theoretically yes, but practically unmeasurable with any reliability. Standard tests cannot validate scores above 150-160. See our page on what an IQ of 200 means.

What was Einstein's IQ?

Einstein's IQ is estimated at approximately 160. Read more on our Einstein IQ page.

Curious where you fall on the scale? Take our free IQ test for an instant estimate. Learn more about how IQ is measured and what every score range means.