64 Personality Types: The 16 MBTI Types, Four Ways Each
The 64 personality types are the 16 MBTI types split four ways by two extra letters: Steady or Sensitive under pressure, and Collaborative or Self-reliant.
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How personality tests work, with our own numbers.
How accurate is an MBTI test? What a retake shows
A well-built MBTI-style test gives the same letter 78–81% of the time per scale; short yes/no tests about 65%. Why your type changes and what to check.
How many questions are in an MBTI test? 93, or 8 to 72
The official MBTI questionnaire has 93 questions; free MBTI-style tests run 8 to 72. Why 12 five-point statements per letter beat 15 yes/no ones.
In Between Two MBTI Types: What a Borderline Letter Means
A borderline MBTI letter means you landed near the middle of that scale, so either side could come out on another day. Read both types; it is not a flaw.