What is the rarest personality type? New data from 19,718 people

The rarest MBTI type, according to the publisher

The Myers-Briggs Company, the publisher of the MBTI assessment, has given two sets of figures on its MBTIonline site. A 2017 article on US data combines three sources: about 900,000 people from the Center for Applications of Psychological Type (CAPT) over 20 years, a national representative sample of about 5,000 people from the publisher, and about 1,000 people from SRI. It names INFJ as the least common type, then ENTJ and INTJ.^[1] A 2023 article gives worldwide figures (the one source it footnotes is the company’s 2020 global survey), in which ISTJ is the most common type and ESTJ the most common extraverted type.^[3]

Two details are worth noticing. First, the figures differ between sources: INFJ is 1.5% in the US data but 2.3% in the global survey, where the publisher itself warns INFJs not to claim “most rare” status just yet, since INFJ men and INTJ women are the least common introverted groups.^[3] Second, they differ sharply by gender: in the US data ENTJ is 2.7% of men but 0.9% of women, and INTJ 3.3% of men but 0.8% of women.^[1] Neither article lists all 16 types, so we do not fill in the rest.

Also note how uneven the MBTI split is. With 16 equally common types, each would be 6.25%. ISTJ alone, at 15.9% in the global survey,^[3] is about two and a half times that, and INFJ in the US is about a quarter of it.^[1]

Our analysis: how common each of the 16 codes is

For a second, fully reproducible answer, we scored the public Open Psychometrics BIG5 dataset: answers to the same 50 public-domain IPIP Big Five items^[4] that 64 Types uses, given by 19,719 online volunteers around 2012.^[2] One record with missing answers was dropped, leaving N = 19,718. This is the same sample that our percentile norms come from. We assigned every person a four-letter code exactly as the 64 Types test does: E/I from Extraversion, N/S from Openness, F/T from Agreeableness and J/P from Conscientiousness, each split at the sample’s median (the 50th percentile).

The four rarest codes, ENTJ, ESTJ, INFP and ISFP, lie between 4.4% and 4.6%. With a sample this size, each share has a margin of error of roughly ±0.3 percentage points, so these four are effectively tied. The two most common codes, ISTP (11.1%) and ENFJ (10.9%), are each about two and a half times as common as the rarest.^[2]

Adding the fifth letter, emotional stability (C = Composed, R = Responsive), gives 32 combinations, which would average about 3.1% each. The rarest are ENTJ-R and INFP-C (1.5% each), then ESTJ-R (1.6%) and ISFP-C (1.7%); the most common are ENFJ-C (7.9%) and ISTP-R (7.3%).^[2]

We do not publish a distribution of all 64 types. The sixth letter, Honesty-Humility (M/A), is measured with IPIP-HEXACO items^[5] and normed on a separate dataset, and nobody in the BIG5 sample answered those questions, so there is no data on how the sixth letter combines with the other five. Any “rarest of the 64 types” figure would have to be invented, so we do not give one.

Why some combinations are rarer: correlated traits

Because every letter splits its trait at the median, each letter on its own is held by roughly half the sample: 48.6% to 50.4% for the four base letters here (not exactly 50%, because many people score exactly at the median and the tie has to go one way). If the four traits were unrelated, every code would therefore land close to 6.25%, between about 5.8% and 6.7% in this sample.^[2] The real spread, from 4.4% to 11.1%, comes from the way the traits go together.

In this sample all five Big Five scores correlate positively with each other. The correlations between trait scores are:^[2]

• Extraversion and Agreeableness: r = .33, the strongest link among the four base letters.
• Extraversion and Emotional Stability: r = .26, and Conscientiousness and Emotional Stability: r = .26.
• Agreeableness and Conscientiousness: r = .18; Extraversion and Openness: r = .17.
• The rest are small: Openness with Agreeableness .12, Extraversion with Conscientiousness .11, Agreeableness with Emotional Stability .11, Openness with Emotional Stability .10, Openness with Conscientiousness .09.

With every link positive, the two codes that agree with all of them, all-high ENFJ and all-low ISTP, are the most common. The four rarest codes all go against the strongest link: ENTJ and ESTJ combine Extraversion with lower Agreeableness (E with T), and INFP and ISFP combine Introversion with higher Agreeableness (I with F). The same logic explains the fifth letter: Emotional Stability goes with Extraversion and Conscientiousness, so the extraverted, organized ENTJ and ESTJ are rarer with R, and the introverted, flexible INFP and ISFP are rarer with C.

Why are the MBTI figures so much more uneven? The two sets of numbers are not measuring the same thing. When McCrae and Costa compared the MBTI with a Big Five inventory, its four scales corresponded strongly to Extraversion and Openness and moderately to Agreeableness and Conscientiousness, and none of them captured Neuroticism.^[6] Our letters split each trait at the median by design; the MBTI uses its own questions and scoring rules. Different questions, scoring rules and samples give different frequencies, so an INFJ on one test is not guaranteed to be an INFJ on the other.

How far to trust these numbers

• Our sample is not representative. The BIG5 data come from volunteers who took a free online test: 61% women, median age 22, from more than 150 countries and territories, with 44% in the United States.^[2] Treat our percentages as a description of this sample, not of the world’s population.
• The publisher’s figures are country- and sample-specific. The 2017 numbers are US-only, as the article itself stresses,^[1] and they differ from the worldwide figures in the 2023 article.^[3]
• Most people are near the middle. Scores on these traits pile up around the center rather than falling into two separate camps,^[7][6] so a small change in score can change a letter and a person’s type on retest.^[8] The rarity of a code is partly a property of where the lines are drawn.
• MBTI type and 64 Types code are different measures. The letters look the same, but they correspond only partly: strongly for E/I and N/S, moderately for F/T and J/P.^[6] See MBTI vs the Big Five.

What this means for you

A rare code is not a sign of a rare mind, and a common one is not a sign of an ordinary one. In our data, rarity follows directly from trait correlations: an extravert who is also tough-minded, or an introvert who is also warm, is simply a less frequent combination of ordinary traits. Each trait on its own is shared by about half of people.

Rarity does not tell you anything about ability, success or compatibility. A letter only says which side of the median you are on, which is why 64 Types reports a percentile for every trait alongside the code. If you are within about 10 points of the 50th percentile on a trait, your letter is flagged as borderline and we show the code you would have with the other letter. See how the 64 Types test works.

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