IQ 187: A Number Beyond the Reach of Modern Tests

What an IQ of 187 would mean

On the standard scale, with a mean of 100 and a standard deviation of 15, a 187 lies 5.8 standard deviations above average. The normal curve puts the share of people at or above that point at about 3.3 in a billion: 1 in 301.6 million. Applied to a world population of roughly 8.3 billion, that yields about 27 people.

That figure rests on an assumption. It presumes the bell curve holds exactly almost six standard deviations out. Nobody has verified that, because no norm group has ever been large enough to check.

Rarity at the edge of the curve

Out here, two points more than double the rarity. At 200, the curve predicts one person in 76 billion, several times the planet's population. Compare IQ 185, IQ 186 and IQ 190; the arithmetic is laid out on the IQ rarity chart and in IQ 200 and above.

The 160 ceiling

The WAIS-IV, the standard adult test, reports full-scale scores from 40 to 160, four standard deviations either side of the mean. Its norms come from 2,200 adults aged 16 to 90. In a sample that size, statistics predict roughly one person at 150 or above. The top of the scale is therefore an extrapolation, and a score of 187 lies far beyond it: no combination of answers produces it.

The testing literature says as much. The highest standard score on most IQ tests is 160, about the 99.997th percentile, and reports of scores much higher than 160 are generally considered dubious. The bands and their limits are summarized in IQ scale classification; the ceiling score itself is covered at IQ 160.

Source one: the old ratio IQ

The original IQ was a ratio. In 1912 the German psychologist William Stern proposed dividing a child's mental age by chronological age and multiplying by 100. An eight-year-old who performed like a typical 15-year-old scored about 187. Ratio scores spread much wider at the extremes than modern deviation scores, and they break down for adults, whose mental-age growth levels off.

Leta Hollingworth's 1942 book Children Above 180 IQ Stanford-Binet shows how rare even ratio scores this high were. In 23 years of searching New York City and its metropolitan area, she found only twelve children who tested at or above 180. Those were ratio figures from the early Stanford-Binet, not deviation IQs, and they cannot be converted into today's scale. The best-known ratio-score record is discussed at IQ 228.

Source two: extended norms and unsupervised tests

Some children's tests now reach higher. In November 2019, Pearson published extended norms for the WISC-V that raise composite scores from a ceiling of 160 to a maximum of 210. They are meant for children who hit the top scaled score of 19 on one or more subtests. Critics note that such extended norms are not based on well-validated data, so the figures they produce are rough rankings rather than precise measurements.

The remaining source is the unsupervised “high-range” test, normed on small, self-selected groups. Mensa will not accept online results, and neither should a careful reader. Are online IQ tests accurate? explains why.

Is 187 a good IQ, or a meaningful one?

The question outruns the instruments. Any claim that an adult scored 187 on a standard, supervised test deserves skepticism. No verified person holds that score, and figures of this size attached to celebrities online are unsourced.

Researchers who study the most able young people use a different method: above-level testing. The Study of Mathematically Precocious Youth gave the SAT, a test built for older students, to children around 13, spreading out the top 1 percent where age-level tests hit their ceiling. For membership purposes the top end is irrelevant: Mensa requires only the 98th percentile, a Wechsler score of 130, as set out in how to join Mensa. Records and claims at the top are reviewed in the highest IQ ever recorded.

What a credible high score looks like

A credible report from a licensed psychologist gives a full-scale score within the test's range, a confidence interval, the test edition and its norm year. At the very top it will read 160, or flag that extended norms were used. Our free IQ test is a practice screener; like every online test, it cannot measure this range.

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.