The 64 personality types come from six letters instead of four. The familiar MBTI letters (E/I, N/S, T/F, J/P) give the 16 base types. Two more, written after a dash, split each one four ways: how you handle pressure, Steady (A) or Sensitive (T), and whether you lean on others or handle things yourself, Collaborative (C) or Self-reliant (S).
What the two extra letters add
The four MBTI letters describe how you take in the world and make decisions. They say little about two things people notice most in daily life: how you hold up when things go wrong, and who you turn to when they do.
Pressure: Steady (A) or Sensitive (T). Steady means things take longer to reach you, and pressure rarely knocks you off balance. Sensitive means things reach you fast and fully; you notice what could go wrong, which keeps you alert. Neither is better. A Steady INTJ and a Sensitive INTJ plan the same way and feel the week very differently.
Support: Collaborative (C) or Self-reliant (S). Collaborative means you think and recover best with people around you. Self-reliant means you carry things yourself and work them out before involving anyone. Two people with the same four letters can sit at opposite ends here, and it shows in how they ask for help, or don’t.
How to read a code
Take INFP-TC. The four letters before the dash are the base type: INFP, The Poet. Reserved, Intuitive, Heart, Flexible. The two letters after the dash are read as their own pair: T for Sensitive under pressure, C for Collaborative, leaning on others. So INFP-TC is a Poet who feels things fast and fully and recovers best in company: The Tender Poet.
One thing to watch. The letters after the dash reuse two letters from the front. T before the dash means Head; T after it means Sensitive. S before the dash means Hands-on; S after it means Self-reliant. Read the pair after the dash on its own, and the code is clear. The four possible pairs are AS, AC, TS and TC.
If a letter in your result sits near the middle, the result says “In between” rather than forcing a side; what an in-between letter means covers how to read it.
The four groups
The 16 base types fall into four groups by their middle two letters, the ones that shape how you take in the world and weigh a decision.
| Group | Letters | Attention and decisions |
|---|---|---|
| The Mapmakers | NT | Intuitive and Head |
| The Gardeners | NF | Intuitive and Heart |
| The Keepers | SF | Hands-on and Heart |
| The Builders | ST | Hands-on and Head |
The 16 base types
The Mapmakers (NT)
| Type | Name | In one line |
|---|---|---|
| INTJ | The Navigator | Decided three weeks ago. Walking there quietly |
| INTP | The Alchemist | Needs to know how it works more than it needs it to work |
| ENTJ | The Strategist | Says what happens next before the room knew it was open |
| ENTP | The Spark | Argues the other side to see if it holds |
The Gardeners (NF)
| Type | Name | In one line |
|---|---|---|
| INFJ | The Lighthouse | Knew how you were before you said it |
| INFP | The Poet | Stayed in the shower until the song line made sense |
| ENFJ | The Guide | Already planned the weekend, and who needs a ride |
| ENFP | The Firefly | Three new ideas before the hair was dry |
The Keepers (SF)
| Type | Name | In one line |
|---|---|---|
| ISFJ | The Confidant | Remembers what you said once, and shows up with it |
| ISFP | The Artist | Lives in what’s in front of them, and makes it better |
| ESFJ | The Hearth | The one who noticed who was cold, and brought a blanket |
| ESFP | The Bonfire | The reason the evening turned into a good one |
The Builders (ST)
| Type | Name | In one line |
|---|---|---|
| ISTJ | The Anchor | Said Tuesday, done Tuesday, spare key in the drawer |
| ISTP | The Climber | Already under the hood while they were still explaining |
| ESTJ | The Conductor | The week is sorted, names and times on it |
| ESTP | The Pilot | Already moving, working out the route on the way |
Four variants of every type
Each base type splits into four variants, named after the base and colored by the two letters after the dash. The Poet becomes The Quiet Poet (AS), The Sunday Poet (AC), The Night Poet (TS) or The Tender Poet (TC). Every base type gets four variants the same way, each with its own name. Once you know your base, read your variant as a shade of it rather than a different person.
One example from each group:
- Mapmakers: INTP-AS, The Quiet Alchemist, Steady and Self-reliant.
- Gardeners: ENFP-TC, The Wild Firefly, Sensitive and Collaborative.
- Keepers: ISFJ-AC, The Warm Confidant, Steady and Collaborative.
- Builders: ESTP-TS, The Rain Pilot, Sensitive and Self-reliant.
Every base page links to its four variants, and every variant page links back to its base and to the types one letter away. The full list is on the types page.
The honest cost of more letters
More letters mean a finer picture and more chances for one letter to land differently on another day. We measured this on 60,000 real answer sheets drawn from the same Johnson IPIP-NEO data as the reference group of more than 135,000 people, using two equivalent sets of research statements per scale.
- Per letter, this test lands on the same side in both sets about 81% of the time (estimated). A 20-question yes-or-no format comes out around 65%.
- All six letters the same in both sets: only 28%. Every extra letter multiplies the chance of a flip.
- That is why close calls are shown as in-between instead of forced. With that rule, only 4–7% of people per scale see a clear letter flip to the clear opposite. Across the four MBTI letters, 82% see no clear flip; across all six, about 7 in 10.
Both sets were answered in one sitting, so a real retake weeks later agrees somewhat less. How it was measured is on the how it works page, and how accurate is an MBTI test goes deeper into what the numbers mean for you.
MBTI is a registered trademark of The Myers-Briggs Company; this test is not affiliated with it. It measures the same four preferences with public research statements and adds two scales of its own.
Six letters, 72 statements, about 10 minutes, nothing to sign up for. Take the free test.