What IQ Is Considered Genius? The Number Nobody Agrees On

There is no official genius IQ threshold. Not one set by a professional body, not one printed in any current test manual, and not one that the people who build IQ tests would defend. The number you will see most often is 140. Others quote 145, or 160. They disagree by twenty points or more and none of them is a standard.

What follows is where the 140 came from, what the competing numbers actually mean in terms of rarity, and why the word disappeared from professional use altogether.

Where the 140 figure came from

In 1916, Lewis Terman published The Measurement of Intelligence, the book that introduced the Stanford-Binet test to an American audience. It contained a classification table, and the top row of that table read: “Above 140: ‘near’ genius or genius.”

Newspapers reprinted that row. Popular books reprinted it. It escaped into general usage and has stayed there for over a century. That single line is the entire origin of the idea that 140 is where genius begins.

What almost never travelled alongside it was Terman’s own warning, in the same book, that the boundaries between such groups are “absolutely arbitrary, a matter of definition only.” He was drawing lines for administrative convenience and said so. His readers took the lines for discoveries about human beings.

There is also a technical problem that makes the 1916 threshold unusable even on its own terms. Terman’s Stanford-Binet used a ratio IQ: mental age divided by chronological age, multiplied by 100. That works after a fashion for children and breaks down entirely for adults, because chronological age keeps rising after mental ability plateaus. David Wechsler replaced it in 1939 with the deviation IQ used today, which simply compares you with age-matched peers on a normal curve. A 1916 “140” and a modern 140 are not the same quantity, so quoting the old threshold against a current score is mixing currencies.

The competing thresholds and what they mean

Setting aside which label anyone attaches, here is what the commonly quoted numbers actually represent in terms of how rare they are, on a modern scale with a mean of 100 and a standard deviation of 15:

Notice how fast the rarity column moves. The twenty points between 140 and 160 take you from 1 in 261 to roughly 1 in 31,000, which is more than a hundredfold. Small differences in where someone draws the line produce enormous differences in how many people fall above it, which is one reason the conventions never converged.

There is a measurement problem on top of that. Above about 130, standardisation samples contain very few people, so the norms are built on thin data and different tests diverge sharply. The arithmetic behind that is set out in our guide to an IQ of 140. In short, the scores being used to define genius are measured less precisely than any others on the scale.

Why no modern test says “genius”

The term was not formally repudiated so much as quietly dropped. Several things pushed it out:

• It described output, then got attached to input. Genius had always meant remarkable achievement. Applying it to a test score redefined it as a capacity, which is a different claim and a much weaker one.
• The ratio-IQ arithmetic that produced the original figures was abandoned. Once deviation IQ replaced it, the old thresholds no longer referred to anything measurable.
• Value-laden labels fell out of favour generally. The Wechsler family moved to neutral descriptors with the WISC-V in 2014 and kept them for the WAIS-5 in 2024, replacing “Very Superior” with “Extremely High”. A label like genius was never going to survive that shift.
• It did not predict what people assumed. Terman’s own longitudinal study of high scorers produced no Nobel laureates, while two children he screened and rejected for scoring too low later won one.

What psychologists use instead

Clinical practice uses descriptive bands with no value claim attached. On the WAIS-IV, 130 and above is Very Superior. In the WISC-V and WAIS-5 the same band is Extremely High. That is the top category, it has no ceiling, and it covers everyone from a 130 to the highest score the test can produce.

Educational settings use gifted, conventionally starting at 130. Some writers subdivide that into moderately, highly, exceptionally and profoundly gifted, but those tiers were invented by individual authors and contradict each other by fifteen points or more, as covered in our guide to an IQ of 135.

The common thread is that professionals describe where a score sits in the distribution and leave the interpretation to context. Nobody writing a report today tells a patient they are a genius.

Is Mensa a genius society?

It is regularly described that way in the press and it does not describe itself that way. Mensa has one admission criterion: a score at or above the 98th percentile on a supervised standardised test. That is IQ 130 on the Wechsler scale and 132 on older Stanford-Binet scales.

The 98th percentile is the gifted threshold, well below any of the numbers people quote for genius. Roughly 1 in 44 people would qualify if everyone sat a supervised test, which is around 1.8 million people in the UK alone. The full process is covered in our guide to joining Mensa.

What IQ is genius for a child?

The same conventions get applied, and they need more caution with children rather than less.

Childhood scores are less stable than adult scores, particularly before about age eight. More importantly, the very high childhood figures that circulate historically came from the ratio formula, which could produce spectacular numbers for young children with no modern equivalent. A child of six performing like a twelve-year-old scored 200 on that arithmetic. On a deviation scale the same performance produces a far lower and far more meaningful number.

In practice, school gifted programmes use 130 as the usual threshold, with individual districts and authorities varying between roughly 120 and 135, and most now combining the score with achievement data, teacher assessment and portfolio evidence rather than relying on the number alone.

The highest IQ ever recorded

The only figure any record-keeping body ever actually listed belongs to Marilyn vos Savant, entered in Guinness World Records at 228 and printed as the world’s highest in every edition from 1986 to 1989.

It is worth understanding exactly what that number is. She sat an adult-level Stanford-Binet in September 1956, aged 10, and produced a mental age of 22 years and 11 months. Apply the ratio formula:

22.9 years of mental age ÷ 10 years of actual age × 100 = 229

That reproduces the published figure almost exactly. The 228 is not a measurement of how far above other adults she scored. It is a statement that a ten-year-old performed like a young adult, expressed in a formula that no longer exists in testing. There is no modern deviation score equivalent, because a modern test would simply have reported that she was off the top of the childhood norms.

Guinness appears to have reached the same conclusion. They retired the category in 1990 on the grounds that the numbers were too inexact to rank, and it has never returned.

Every larger figure you will encounter, including the 250 to 300 sometimes attached to William James Sidis, is a posthumous estimate rather than a test result. Nobody administered anything to Sidis that produced those numbers. As a general rule, treat any quoted IQ above about 160 as either an obsolete ratio score, a retrospective guess, or an unverified claim, until someone names the test.

Does a high IQ make you a genius?

No, and the reason is more interesting than the answer.

Genius, in the sense people actually use the word, is a judgement made afterwards about a body of work. It describes what someone produced and how it changed a field. An IQ score describes how a person performed on a reasoning test on one particular afternoon. These are different kinds of claim, and no arithmetic converts one into the other.

The evidence supports the weaker and more useful version: high cognitive ability makes exceptional work more likely, and the effect does not disappear at the top of the range. What it cannot do is tell you in advance who will produce it. The outcomes people find most impressive are rare enough that no test will reliably identify them beforehand, which is exactly what Terman discovered when his high scorers grew up.

Which leaves the honest position. If you are above 140 you have unusually strong cognitive raw material and you are in roughly the top 1 in 261 people. Whether anyone ever calls you a genius depends on what you build with it, and that question has never been answerable from a score.

Frequently asked questions

The bottom line

There is no genius IQ threshold, only conventions that disagree. The 140 everyone quotes comes from one row in a 1916 classification table whose author described its boundaries as absolutely arbitrary, and it was calculated using a formula that testing abandoned in 1939. No test in professional use today carries the label at all.

If you want a number that means something, use the percentile. 130 puts you in the top 2%, 140 in the top 0.4%, 160 in roughly the top 1 in 31,000. Those figures describe something real. The word attached to them describes only which book somebody read.