Founders who search for a "cofounder personality test" usually want an answer to a narrower question: will this specific person and I be able to build a company together? A personality test can help with part of that question. It cannot answer it on its own, because it describes one person at a time.
This article explains what personality tests measure, what the research behind them supports, and where a working-style assessment for a founder pair fits. It does not rank tests or claim that one framework predicts startup success.
If you already have a potential cofounder, the free CofounderFit assessment compares both founders' working preferences across 8 dimensions. Read the methodology first if you want to know how the score is calculated and what it leaves out.
What a personality test measures
A personality test asks one person to describe their own habits and preferences, then summarizes the answers as traits or types. The two frameworks founders meet most often are the Big Five and the Myers-Briggs Type Indicator (MBTI).
The Big Five (also called the five-factor model) describes personality on five continuous dimensions: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism. Each person gets a position on each scale rather than a category. McCrae and John's introduction to the five-factor model summarizes how researchers arrived at these five dimensions and how they are used.
The MBTI sorts people into one of 16 four-letter types based on four preference pairs, such as introversion and extraversion. McCrae and Costa compared the MBTI with the five-factor model and argued that MBTI results are better interpreted through that broader trait framework than through Jungian type theory.
Both describe an individual. Neither was designed to compare two specific people who are about to share equity, roles, and decision rights.
What the research supports, and what it does not
Personality research does say something about entrepreneurs as a group. A meta-analysis by Zhao and Seibert in the Journal of Applied Psychology found that, compared with managers, entrepreneurs scored higher on conscientiousness and openness to experience and lower on neuroticism and agreeableness.
That is a group-level difference between two occupations. It does not tell you whether a given founder will succeed, and it says nothing about whether two founders will work well together. Two people can both score high on conscientiousness and still disagree on how fast to decide, how much risk to take, or who owns the product roadmap.
The organization that publishes MBTI guidance is explicit about one boundary. The Myers & Briggs Foundation's code of ethics states that using MBTI results to screen job applicants is unethical practice. Choosing a cofounder is not hiring, but the same logic applies: a type label should not be the reason you accept or reject a partner.
What a working-style assessment compares instead
A working-style assessment asks about behavior in situations a founding team will actually face, then compares two people's answers side by side. The useful questions are concrete:
- Decision making: Do you decide with incomplete data, or wait for more evidence? Who breaks a tie?
- Risk: How long can you go without a salary? How do you react when a bet fails?
- Stress and conflict: Do you push for an immediate conversation, or need time before discussing a disagreement?
- Leadership and roles: Do you expect one final decision-maker, or shared authority?
- Values and priorities: What would you trade for growth? What would you refuse?
- Vision and execution: Who keeps the long-term direction, and who turns it into weekly output?
The output is not a type for each person. It is a map of where the two founders are aligned, where they differ in a way that can be complementary, and where the difference needs an explicit agreement.
A fictional example
The following pair is invented to illustrate the difference.
Maya and Leo are planning a B2B software company. Both took a free online personality test and got similar results: high conscientiousness, high openness. They concluded they were compatible.
A working-style comparison shows a different picture. Maya wants to ship a paid pilot within six weeks and decide pricing from customer reactions. Leo wants to finish the security review before any customer touches the product. Both preferences are conscientious; they point in opposite directions. Neither personality result revealed it, because neither test asked about launch timing, risk, or who has the final say on product readiness.
The useful next step for Maya and Leo is not a better type label. It is a written decision: who owns the launch call, what "ready" means, and how they will revisit the decision after the pilot.
When a personality test is still useful
A personality test can help a founder understand their own defaults before the cofounder conversation. It gives you vocabulary for preferences you may never have named, such as needing time alone to recover after conflict.
Use it as preparation, not as evidence about the partnership:
- Take an individual test if it helps you describe yourself honestly.
- Turn each result into a question for your potential cofounder, such as "I tend to avoid conflict; how do you want me to raise disagreements?"
- Compare working preferences directly with a pair assessment or the cofounder questions checklist.
- Test the relationship in real work with a cofounder trial project.
- Write the decisions down in a cofounder agreement template before you split equity.
How CofounderFit handles personality traits
CofounderFit's assessment includes Big Five-style items, and some of them feed the dimension scores shown on each founder's profile. The pair compatibility score does not weight the Big Five traits themselves. The score weights seven working dimensions: values, leadership, risk, communication, work approach, decision making, and stress. Vision and execution is not weighted as a separate dimension: its complementarity is one third of the work approach score. These are differences founders can discuss and turn into decisions. The methodology page lists the dimensions, the weighting, and the limits of the score, including that it relies on self-reported answers and is not a psychological diagnosis.
If you want the full framework, read the cofounder compatibility test: 8 dimensions to check before equity.
Key takeaways
- A personality test describes one person. A founder decision depends on two people and how they work together.
- Big Five research supports group-level differences between entrepreneurs and managers, not predictions about a specific founder pair.
- The Myers & Briggs Foundation's ethics guidance rules out using MBTI results to screen job applicants.
- Compare concrete working preferences, test them in real work, and write the resulting decisions down.
Sources
- McCrae, R. R., & John, O. P. (1992). An introduction to the five-factor model and its applications. Journal of Personality, 60(2), 175–215.
- 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, 57(1), 17–40.
- Zhao, H., & Seibert, S. E. (2006). The big five personality dimensions and entrepreneurial status: A meta-analytical review. Journal of Applied Psychology, 91(2), 259–271.
- The Myers & Briggs Foundation. MBTI code of ethics.