I scored 51% on one scale — am I really that letter?

Treat anything near 50% as undecided, not as an identity. Retest after 2–4 weeks, answer about your unstructured free time rather than work, and compare both neighbouring codes — every type has exactly one neighbour with three letters in common.

Can my type change over time?

The letters can flip on any scale where your clarity sits near the middle, and that is normal rather than a glitch. A high-clarity preference — a 70% or 80% score — rarely reverses between sittings.

Why did two different tests give me different types?

Because they count differently. A 93-item forced-choice form, a 240-item facet inventory like the NEO-PI-R and a quick online quiz are different machines; compare the clarity percentages behind each result instead of the letters alone.

Is one type better, smarter or rarer than the others?

No — the system has no ranking built in. By construction each letter appears in 8 of the 16 types, and a code describes preference, not ability, character or mental health.

Sixteen types — one is yours

Psychotyp — Psychological personality typing: the 16 | psychotyp.com

The 16 personality types are shorthand codes built from four either–or scales: extraversion or introversion, sensing or intuition, thinking or feeling, judging or perceiving. Multiplied out as 2 × 2 × 2 × 2 they give exactly sixteen combinations, and this guide shows how to read each code and how to work out which one fits you. The method below takes about 15 minutes with a standard 93-item form.

Four coins, sixteen codes

The whole system is four either–or scales multiplied together: 2 × 2 × 2 × 2 = 16 four-letter codes. Learn the four scales and you can read any code without a lookup table.

Score it like an instrument

A result is four clarity percentages from 0 to 100%, gathered by a 93-item forced-choice form in about 15 minutes. Near 50% means undecided; the fix is a retest, not a guess.

Look under the hood

Each code unpacks into a four-function stack — dominant, auxiliary, tertiary, inferior — drawn from eight functions. The dominant and auxiliary must sit in opposite attitudes; that rule is your checksum.

Change one letter and you land on the single type that shares your other three — in this system no code stands alone.

A 70% T is not a verdict; it is a count — 70 of 100 answers leaned toward thinking.

What are the 16 personality types?

They are the sixteen possible combinations of four either–or scales, written as four-letter codes such as INTJ or ESFP.

Each scale is a dichotomy — a preference with two poles. The first asks where attention flows: outward to people and action (E) or inward to ideas and reflection (I). The second asks what you trust first: concrete sensory facts (S) or patterns and possibilities (N). The third asks how you decide: by impersonal logic (T) or by values and human impact (F). The fourth asks how you like to close: planned and settled (J) or open and adaptable (P).

Because every scale has exactly two poles, the codes multiply out as 2 × 2 × 2 × 2 — sixteen combinations, no more, no fewer. The arithmetic has a useful consequence: each single letter appears in exactly 8 of the 16 types, so no letter is exotic on its own.

The grid is tightly connected. Every type shares three of its four letters with exactly one other type — a nearest neighbour one flip away. That is why a borderline result is informative: it points you at one specific neighbouring code to compare, not into a fog of maybes.

The bench in four drawings

Schematics for the scales, the stack, the clarity band and the timeline — each ties back to a number in the table below.

Two dates that built the system

The key terms of this guide, drawn to one scale

Every number in the system

Every number used on this bench, in one place.
Part of the system	What it counts	Size and numbers
Four dichotomies	Preference on 4 either–or scales	2 poles per scale → 16 codes
One letter's share	How often a letter appears	8 of 16 types (50%)
Nearest neighbour	Types differing by one letter	Exactly 1 type shares 3 of 4 letters
MBTI Form M	Four-scale preference inventory	93 forced-choice items · ~10 s each · ~15 min
Function stack	Processes behind one type	4 positions drawn from 8 functions
Big Five (NEO-PI-R)	Trait factors and facets	5 factors · 30 facets · 240 items (8 per facet)
Enneagram	Motivational types	9 types
Kiersey temperaments	Groups within the sixteen	4 groups × 4 types

Every number used on this bench, in one place.

Objections heard at the bench

I scored 51% on one scale — am I really that letter?: Treat anything near 50% as undecided, not as an identity. Retest after 2–4 weeks, answer about your unstructured free time rather than work, and compare both neighbouring codes — every type has exactly one neighbour with three letters in common.
Can my type change over time?: The letters can flip on any scale where your clarity sits near the middle, and that is normal rather than a glitch. A high-clarity preference — a 70% or 80% score — rarely reverses between sittings.
Why did two different tests give me different types?: Because they count differently. A 93-item forced-choice form, a 240-item facet inventory like the NEO-PI-R and a quick online quiz are different machines; compare the clarity percentages behind each result instead of the letters alone.
Is one type better, smarter or rarer than the others?: No — the system has no ranking built in. By construction each letter appears in 8 of the 16 types, and a code describes preference, not ability, character or mental health.