letters as a nickname
The four-letter code
E/I · N/S · T/F · J/P
ENFP and Ne–Fi look like two languages for one psyche, and they are, once you know what each letter is actually marking. The four-letter code is a nickname for a function stack, not a second test.
Two nicknames for the same stack
Function-first circles often name a type by its top two: Ne–Fi, Ti–Ne, Ni–Te. Myers-Briggs and most internet quizzes use four letters: ENFP, INTP, INTJ. This site scores the functions, then reports a four-letter type as a reading aid. It is not the official MBTI® instrument.
If you already wear a four-letter code and want to know which functions it implies — or you have a stack and want the letters other people will recognise — this is the conversion.
What each letter is saying
E or I tells you whether the first function is extraverted or introverted.
N or S tells you which perceiving function sits higher in the stack.
T or F tells you which judging function sits higher in the stack.
J or P tells you whether the first extraverted function is a judging function or a perceiving function. It does not mean “organised” or “spontaneous.” For an introvert, that last letter describes the auxiliary, not the Hero / Heroine — which is why an INFJ can be a dominant perceiver, and an INFP a dominant judger, while the letters suggest the opposite.
Four-letter code to stack
Take ENFP.
Everyone has S, N, T, and F. E means the first function is extraverted, so the attitudes run eiei. N and F are the two higher functions; S and T will sit lower. P means the first extraverted function is perceiving, so that extraverted lead must be Ne, and the introverted partner in the top two is Fi.
The remaining pair follows the JPPJ / PJJP rule: after Ne and Fi come Te and Si.
ENFP = Ne–Fi–Te–Si. Hero / Heroine Ne, Parent Fi, Eternal Child Te, Inferior Si.
Another: INTJ. I means the lead is introverted (ieie). N and T are the top two. J means the first extraverted function is judging, so that extraverted function is Te, and the introverted lead is Ni. Then Fi and Se.
INTJ = Ni–Te–Fi–Se.
Stack to four-letter code
Take Ni–Fe–Ti–Se.
The middle letters are N and F, because those are the higher perceiving and judging functions: xNFx. The first function is introverted, so the code begins with I: INFx. The first extraverted function is Fe, which is judging, so the last letter is J.
Ni–Fe–Ti–Se = INFJ.
That is the same type as INFP in three letters and in none of its functions. The last letter is doing almost all of the work, which is why letter-only quizzes so often bounce people between those two.
Take the items next
You do not have to perform this conversion before you take the quiz. The statements ask about Ni, Te, Fi, Se as living processes. The four-letter result is a name for the stack those scores resemble. If you have been choosing J or P as a lifestyle, start from the functions instead.