What Is 16Personalities and How Does It Relate to MBTI?
16Personalities is a free online personality assessment created by NERIS Analytics. It draws heavily from the Myers-Briggs framework, the same four binary dimensions (E/I, S/N, T/F, J/P), but adds a fifth axis called Identity: Assertive (A) vs. Turbulent (T). That fifth axis brings the total to 32 possible profiles, though the site still groups outputs into 16 named types (Architect, Campaigner, Mediator, and so on), each assigned a four-letter MBTI-style code.
The two figures above are not the same kind of number, and the difference is the point of this article. The first is a running counter that 16Personalities publishes on its own homepage, where it currently reads more than 1.5 billion tests taken. It comes from the company, not from an independent audit, and it measures reach rather than accuracy. The second comes from a meta-analysis of 138 independent samples and 70,926 people, in which Big Five Conscientiousness, the dimension Cèrcol calls Discipline, correlated with academic performance at a corrected r of .22, with an observed correlation of .19 doi:10.1037/a0014996. One of these numbers tells you how many people took a test. The other tells you what a trait score is worth.
The test is free, takes about twelve minutes, and produces richly written, visually designed type descriptions. That combination, free, fast, visually appealing, emotionally resonant, explains most of its virality. The descriptions are written broadly enough to feel personally accurate to most readers, a well-documented phenomenon in psychology known as the Barnum or Forer effect.
How 16Personalities Became the World's Most-Taken Personality Test
16Personalities consistently ranks among the most-visited psychology-adjacent websites in the world. It has been translated into dozens of languages. Workplace use is common: teams share their types in onboarding documents, Slack bios, and team retrospectives. Its cultural footprint is substantial, "INFJ" and "ENFP" have become common identity markers in online communities.
This reach is worth acknowledging seriously. When a tool becomes this embedded in how people talk about themselves, dismissing it entirely is neither accurate nor useful. Something about it is working.
The Scientific Problems With 16Personalities' Type System
The core scientific problems with 16Personalities are inherited from MBTI, which it closely resembles:
1. Binary types vs. continuous traits. The most empirically well-supported finding in personality science is that personality traits are normally distributed across populations: they are spectrums, not categories. Forcing a continuous dimension like Extraversion/Introversion into a binary creates a false discontinuity. This has been tested directly on the MBTI itself. McCrae and Costa evaluated the instrument against the five-factor model in 468 adults and found no support for the view that it measures truly dichotomous preferences or qualitatively distinct types; what it measures is four relatively independent continuous dimensions doi:10.1111/j.1467-6494.1989.tb00759.x. People who score near the midpoint on any dimension will be arbitrarily assigned to one side or the other, and may receive a completely different type on retesting. For a fuller treatment of why this matters, see what is reliability and validity in personality testing.
2. Test-retest reliability. Because of the binary categorisation problem, a meaningful percentage of people receive different four-letter codes when they retake the test weeks later. The same issue documented with MBTI (see our article on MBTI vs Big Five) applies here. A test that does not reproduce its own results is not measuring a stable trait.
3. Limited predictive validity. This article quotes no validity coefficient for 16Personalities, and that absence is deliberate: there is no substantial independent peer-reviewed literature reporting one. NERIS Analytics has not published external validation studies in the peer-reviewed record, and no independent replication of the instrument's structure or its criterion validity exists to cite. Contrast that with the Big Five, where Conscientiousness alone has been meta-analysed across 138 independent samples for academic performance doi:10.1037/a0014996. The honest statement about 16Personalities is not that it predicts poorly; it is that nobody independent has measured whether it predicts at all. See personality science: evidence-based HR and why it matters.
4. The Barnum effect in written descriptions. The type descriptions on 16Personalities are written to be broadly applicable. Research on the Barnum effect (Forer, 1949) shows that people accept vague, positive personality descriptions as uniquely accurate for themselves even when the same description would apply to most people. This does not mean the descriptions are wrong, but it means personal resonance is not evidence of measurement validity. For more on myths like this one, see five personality science myths that won't die.
Where 16Personalities Gets the Big Five Partially Right
16Personalities is not pure noise. It is built on four axes that a peer-reviewed literature has already shown to carry real trait variance.
The Identity axis (A vs. T) is the one genuinely new dimension. The Assertive/Turbulent axis is described by NERIS as capturing confidence and emotional reactivity, which places it conceptually where the Big Five puts emotional stability, the inverse of Neuroticism (Depth in Cèrcol). That is a sensible place to add a fifth axis, since the four MBTI-derived dimensions leave Neuroticism uncovered. It should be said plainly that this mapping has not been tested in an independent study: it is a reading of what the axis is designed to do, not a measured correlation.
The four inherited dimensions have partial Big Five overlap. This is the part that does rest on published evidence. McCrae and Costa correlated the four MBTI indices with the NEO Personality Inventory, using self-reports and peer ratings from 468 adults, and found that each index measured aspects of four of the five major dimensions of normal personality doi:10.1111/j.1467-6494.1989.tb00759.x. Because 16Personalities uses the same four axes, that result is the best available evidence for the correspondence set out below.
| 16Personalities dimension | Closest Big Five mapping |
|---|---|
| Extraversion (E) vs. Introversion (I) | Extraversion / Presence |
| Intuition (N) vs. Sensing (S) | Openness to Experience / Vision (partially) |
| Thinking (T) vs. Feeling (F) | Agreeableness / Bond (inversely) |
| Judging (J) vs. Perceiving (P) | Conscientiousness / Discipline (partially) |
| Assertive (A) vs. Turbulent (T) | Emotional Stability (inverse of Neuroticism / Depth) |
The table is a structural correspondence, not a table of coefficients. Each axis conflates variance from more than one Big Five factor, and the fifth row is the least evidenced of the five. But the overlap is not zero, and it explains why people generally recognise themselves in the Extraversion half of their code.
It is a gateway. For many people, 16Personalities is their first encounter with the idea that personality can be measured and discussed systematically. That is genuinely valuable. The conversation it opens matters.
Types vs Trait Spectrums: Why the Distinction Matters for Teams
This distinction is worth dwelling on because it underlies most of the scientific criticism of MBTI-adjacent tools.
A type says: you are either X or Y. You are an Introvert or an Extravert. You are an INTJ or an INFJ.
A trait spectrum says: you fall somewhere on a continuous distribution, and your exact position on that distribution predicts specific outcomes in specific contexts.
The type approach is more memorable and generates better stories. The spectrum approach is more accurate and more useful for decisions. Someone who scores 55 on Extraversion and someone who scores 80 will both be typed as "Extravert," but they will behave very differently in a high-stimulation work environment. That difference matters for team design.
Understanding facet-level structure amplifies this further, see what is a facet in personality psychology for how sub-trait resolution adds information that any type system structurally cannot capture.
When to Use 16Personalities, and When Big Five Is the Better Choice
16Personalities is a genuinely excellent conversation starter. It gives people accessible language to discuss their preferences, working styles, and social needs. In a low-stakes context, a team offsite, an onboarding icebreaker, a personal reflection exercise, it can be valuable.
Where it should not be used: hiring decisions, performance evaluation, team composition for high-stakes projects, coaching programmes that require tracking change over time. For those purposes, you need a tool with stable scores, dimensional resolution, and a published validity record. The Big Five, measured through IPIP-based instruments, provides all three. See the best free personality tests for teams in 2026 for a ranked comparison that includes 16Personalities.
If your team has been using 16Personalities as a shared language, you do not have to abandon it entirely. But layering in a proper Big Five assessment, one that gives each person a continuous profile across five validated dimensions, will add information that 16Personalities simply cannot provide.
16Personalities vs Big Five: try the validated alternative free
If 16Personalities has been your team's shared language, it has done something useful: it has made personality a topic you can talk about. The next step is to replace the binary type labels with continuous, facet-level scores that come with published criterion validity.
Cèrcol measures all five Big Five dimensions, including Depth (Neuroticism), which 16Personalities' A/T axis approximates but does not fully capture, using 120 items drawn from the open-domain IPIP item bank. Each person gets a continuous profile, not a four-letter code, meaning the information is preserved rather than collapsed. The Witness peer assessment adds an outside perspective, surfacing the blind spots that self-report alone will always miss.
The assessment is free. It takes about 15 minutes. And unlike 16Personalities, the scoring is transparent, auditable, and grounded in a scientific literature that spans five decades and 50-plus countries. Start at cercol.team, or read about the science behind the instrument first.
Sources
- Poropat, A. E. (2009). A meta-analysis of the five-factor model of personality and academic performance. Psychological Bulletin. https://doi.org/10.1037/a0014996
- McCrae, R. R., & Costa, P. T. (1989). Reinterpreting the Myers-Briggs Type Indicator from the perspective of the five-factor model of personality. Journal of Personality. https://doi.org/10.1111/j.1467-6494.1989.tb00759.x
- 16Personalities, tests-taken counter published by NERIS Analytics: https://www.16personalities.com
- Wikipedia: 16Personalities
- Wikipedia: Big Five personality traits
- Wikipedia: Myers-Briggs Type Indicator
- IPIP: International Personality Item Pool: https://ipip.ori.org