Child Prodigies With the Highest IQ: The Records Examined

The ratio-IQ trap that inflates every prodigy number

Almost all the eye-watering childhood scores share one flaw: they are ratio IQs. The old formula is simple - mental age divided by chronological age, times 100. A four-year-old who performs like an eight-year-old "scores" 200. It looks precise, but it breaks down completely at the top, because a young child can be a few years ahead in measurable skills and the ratio explodes.

Modern tests abandoned that formula by the 1960s in favor of deviation IQ, where 100 is average and every 15 points is one standard deviation, scored against your own age group. On that scale, Kim Ung-yong's ratio 210 corresponds to roughly a deviation IQ of 174 - still remarkable, but 36 points lower and no longer a "world record." Comparing a prodigy's ratio 210 to an adult's deviation 130 is comparing two different rulers - and that confusion is behind most "smarter than Einstein" headlines.

The prodigies, one by one

Adragon De Mello - the "400" that was never a test

The 400 is the most-cited and least-supported number in this whole subject. No standardized test produces a 400; the scale does not go there. The figure traces to his father, Agustin, who claimed the boy talked before six months and did calculus before four, and pushed him relentlessly toward an imagined teenage Nobel Prize. What is real: in 1988 Adragon graduated from UC Santa Cruz at age 11, briefly the youngest US college graduate. What is also documented: some instructors later called his grades borderline, and in a 2000 CBS interview Adragon himself credited his father's drilling more than any innate genius. Treat "400" as folklore.

William James Sidis - a real prodigy, a mythical number

Sidis (1898-1944) may be the most famous prodigy of all, and his 250-300 is the extreme case. There is no record of him ever sitting a standardized IQ test. The number comes from a single second-hand source: psychologist Abraham Sperling reported that Sidis's intelligence had been estimated that high, with no named examiner and no test paper. What is verified is impressive on its own - reading at age two, entering Harvard at 11, and lecturing the Harvard Mathematical Club on four-dimensional geometry that same year. He later withdrew from public life and died an office clerk. The talent was real; the score is a story.

Terence Tao - the one number with real work behind it

Tao is the strongest name here, because his adult achievements are beyond dispute: a Fields Medal in 2006 and a career at the very front of modern mathematics. His "230" comes from a genuine data point - at age 8, in Julian Stanley's talent study, he scored 760/800 on the SAT math section - which researchers back-converted into an IQ from its statistical rarity. But Tao has repeatedly waved this off, saying such tests are "extremely noisy at these scales" and that "greater than 175" is the honest ceiling. When the actual genius says the number is unreliable, believe him.

Kim Ung-yong and Michael Kearney - measured, but with old rulers

Kim's 210 is a real childhood Stanford-Binet result that put him in Guinness, and as a boy he solved calculus problems on live Japanese television. But it is a ratio score (≈174 deviation), and Kim has said plainly that as an adult he never took an official test. He grew up to be a civil engineer and university professor - a quietly successful life he has defended against the "failed genius" framing.

Kearney's 200-plus comes from a book written by his own parents, not an independent lab. What is externally verified is the record itself: a bachelor's degree with honors at age 10 (a Guinness record for youngest college graduate), later master's degrees, a PhD at 22, and two $1 million game-show wins in 2006. Strong evidence of a real prodigy; weak evidence for any exact number.

The modern teen "beats Einstein" headlines

Every year or two a British 11- or 12-year-old - Lydia Sebastian, Yusuf Shah, Nicole Barr, Tara Sharifi and others - "scores 162, higher than Einstein and Hawking." Two things to know. First, 162 is the maximum under-18 score on the UK Mensa Cattell III B paper, and that test uses a standard deviation of 24, not the 15 you see everywhere else - so 162 there is about as rare as roughly 148 on a Wechsler-scale test. Impressive, top ~1%, but not a literal 162 in the usual sense. Second, Mensa itself notes the Einstein and Hawking comparison is meaningless, because neither man is known to have taken any such test.

The honest takeaway

Strip out the ratio inflation, the parental claims and the single-source estimates, and the picture changes. The prodigies were real; the record numbers mostly were not. The one figure with serious work behind it - Tao's - is the one its owner insists you should not trust past "greater than 175." Real modern tests top out around 160-170 by design, so any child-prodigy claim above that came from a method that inflates. The productive move is not to chase a mythical 300 or 400, but to get one honest, current score measured against your own age group and see where it actually sits.

Frequently asked questions

Q: Which child prodigy had the highest IQ?

A: No verified record exists - the highest claims are the least trustworthy. Adragon De Mello's "400" was a father's claim, never a test; Sidis's "250-300" comes from a single second-hand account; Kim Ung-yong's 210 is an inflated childhood ratio score. The names are real prodigies, but the top numbers are estimates and folklore, not measured results.

Q: Why are child prodigy IQ scores so high?

A: Because most use the old "ratio IQ" formula, which inflates young children. Ratio IQ divides mental age by actual age and multiplies by 100, so a child a few years ahead scores 200-plus. Modern deviation IQ scores you against your own age group and abandoned that formula by the 1960s. Kim Ung-yong's ratio 210, for example, equals only about 174 on the modern scale.

Q: Did Terence Tao really have an IQ of 230?

A: That is an extrapolation Tao himself rejects. The number was back-calculated from his age-8 SAT math score of 760/800. Tao has said such tests are "extremely noisy at these scales" and that a more honest statement is simply an IQ "greater than 175." His Fields Medal, not the number, is the real measure of his ability.

Q: How do kids score 162 and "beat Einstein"?

A: 162 is the maximum under-18 score on the UK Mensa Cattell paper, which uses a wider scale. That test has a standard deviation of 24, so 162 there is roughly as rare as 148 on the more common Wechsler scale - top 1 percent, but not a literal 162. And Mensa points out the Einstein comparison is empty, since he is not known to have ever taken an IQ test.

References

• Wikipedia contributors. William James Sidis - documented childhood achievements and the unverified origin of the 250-300 estimate.
• Wikipedia contributors. Kim Ung-yong and Michael Kearney - childhood ratio scores, Guinness records, and adult careers.
• PsyPost. What is the highest IQ ever recorded? The truth behind the numbers - ratio vs. deviation IQ and why extreme childhood scores are unreliable.
• ScienceAlert. 12-year-old girl scores 162 in the Mensa IQ test - on the Mensa maximum score and the flawed Einstein comparison.

Last updated: July 13, 2026