Who Is the Smartest Person in the World?

Trying to figure out who the smartest person in the world is is not easy.

Intelligence is tricky to define, and even harder to measure. 

IQ tests attempt to quantify certain cognitive abilities, but they don’t capture creativity, emotional intelligence, wisdom, or real-world impact. Scores above 160 also become statistically unreliable, and many historical figures never took formal tests at all.

With that in mind, here’s a look at 20 people whose intelligence has been documented or estimated, grouped by reliability and historical significance.

Most Reliably Measured Minds

1. Terence Tao (IQ 225–230)

Terence Tao is often called the “Mozart of mathematics,” and for good reason. He was solving calculus problems by age seven, and earned a PhD from Princeton at twenty.

At 21, he was already a senior lecturer at University of California, Los Angeles. His IQ comes from well-documented testing, and decades of groundbreaking research back it up.

2. Marilyn vos Savant (IQ 228)

Marilyn vos Savant once had the highest recorded IQ on the Stanford–Binet test, a fact that earned her a spot in the Guinness Book of World Records. 

Beyond the numbers, she’s famous for her “Ask Marilyn” column, where she tackled logic puzzles that even seasoned mathematicians found tricky.

3. Christopher Hirata (IQ 225)

Christopher Hirata was a child prodigy, mastering calculus as a kid and working with NASA while still a teenager. He earned a physics PhD from Princeton and is considered one of the people with the highest reliably measured IQs.

4. Sho Yano (IQ ~200)

Sho Yano learned to read at two, entered college at nine, and earned both an MD and a PhD before his mid-twenties. His IQ comes from standard tests, but his early academic milestones are what really impress.

5. Jacob Barnett (IQ ~170)

Diagnosed with autism as a toddler, Jacob Barnett went on to publish original research in theoretical physics and earn a PhD at a young age. His IQ isn’t the highest on this list, but his creative thinking shows that raw intelligence isn’t the whole story.

High but Disputed IQ Scores

6. YoungHoon Kim (Claimed IQ 276)

In 2024, the Giga Society reported that YoungHoon Kim may have the world’s highest IQ. His score comes from high-range experimental tests rather than standard ones, so it’s impressive but controversial.

7. William James Sidis (Estimated IQ 250–300)

William Sidis entered Harvard at eleven and amazed everyone with his intellect. He was described as a once-in-a-generation mind, though no modern IQ test captured it. Estimates vary, but his early achievements remain legendary.

8. Christopher Michael Langan (IQ ~195)

Christopher Langan scored at the extreme high end on multiple IQ tests. Despite an unconventional life path, his Cognitive Theoretic Model of the Universe drew both curiosity and skepticism.

9. Rick Rosner (IQ 190–198)

Rick Rosner is unusual in being very open about his testing. He has taken dozens of high-range IQ tests, and his results consistently place him among the most intelligent modern humans.

Historical Geniuses

10. Isaac Newton (Estimated IQ 190–200)

Newton co-invented calculus and formulated the laws of motion. His intelligence is measured by impact rather than test scores, but few minds have changed human knowledge so profoundly.

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11. Albert Einstein (Estimated IQ ~160)

Einstein didn’t care for IQ tests, yet his work on relativity reshaped physics. His estimated IQ is lower than many expect, showing that numbers can’t capture genius.

12. Leonardo da Vinci (Estimated IQ 180–220)

Leonardo da Vinci was an artist, inventor, engineer, and anatomist centuries ahead of his time. His notebooks reveal a mind capable of seeing connections most people never notice.

13. Marie Curie (Estimated IQ 180–200)

The only person to win Nobel Prizes in two different sciences, Curie combined relentless curiosity with experimental brilliance, showing that intelligence isn’t just about numbers.

14. Johann Wolfgang von Goethe (Estimated IQ 210–225)

Goethe excelled in literature, philosophy, and science. Based on lifetime achievements, some researchers estimate his intelligence as among the highest in history.

Strategic Thinkers and Polymaths

15. Garry Kasparov (IQ ~190s)

Garry Kasparov dominated chess through extraordinary pattern recognition and strategic depth—skills that IQ tests can’t fully capture.

16. Nikola Tesla (Estimated IQ 160–310)

Tesla’s IQ estimates vary widely, reflecting how hard it is to measure visionary thinking. His inventions, from AC electricity to wireless technology, speak for themselves.

17. Ada Lovelace (Estimated IQ ~160)

Ada Lovelace saw that machines could manipulate symbols, not just numbers—a conceptual leap that makes her the world’s first computer programmer in spirit.

18. John Stuart Mill (Estimated IQ 180–190)

Philosopher, economist, and reformer, Mill showed extraordinary intellectual development from childhood, shaped by intense early education.

19. Hypatia of Alexandria (Estimated IQ 170–210)

A mathematician and philosopher in ancient Alexandria, Hypatia taught, invented, and published in an era when few women had access to knowledge.

A Modern Prodigy

20. Ainan Celeste Cawley (Reported IQ ~263)

Ainan Cawley displayed advanced abilities in chemistry, math, and music before he was a teenager. His IQ is high, though like many prodigies, the number comes with caveats.

Why ‘Smartest Person’ Doesn’t Exist

IQ tests only capture part of intelligence. Scores above 160 are increasingly unreliable, and creativity, emotional insight, and real-world impact can’t be boiled down to a single number. That’s why Guinness retired its “highest IQ” category.