IPIP stands for the International Personality Item Pool. It is a free collection of personality questions in the public domain. Anyone can copy them, translate them, or publish them. No permission, no fee. Most of the Big Five personality tests you find online are built from it.
The quick answer
| Question | Answer |
|---|---|
| What it is | A public library of personality questions, not a single test |
| Who built it | Lewis R. Goldberg, launched online in 1998 with an NIMH grant |
| How big | Over 3,000 questions and more than 250 ready-made scales |
| What it costs | Nothing. No fee, no license, no permission needed |
| Tests you have heard of | IPIP-50, IPIP-NEO-120, IPIP-NEO-300 |
The Oregon Research Institute hosts the pool at ipip.ori.org. The terms are unusually plain for academic work. Use the items for any purpose, commercial ones included, without asking anyone.
It is a library, not a test
This is the part that confuses people. It also explains why all the names look so similar.
The IPIP is not a questionnaire you take. It is the raw material. Researchers pull items from the pool, group them into scales, check statistically that the scales hold together, then publish the result under a name of their own choosing. Each result gets its own name. That is why IPIP-50, IPIP-120, IPIP-300 and IPIP-NEO all turn up in one set of search results looking like variants of a single thing. They are different tests, drawn from one source.
So "taking the IPIP" is a bit like "reading the library". You cannot. You take one of the questionnaires built from it.
Where it came from, and why it is free
Personality research had a problem. The best-validated questionnaires were commercial products, sold by publishers who had every reason to keep the questions locked up and every legal means to do it. A researcher had to buy one, could not change a word of it, and could not print the questions in a paper. That made replication hard. Translation, harder still.
Goldberg's answer was to build an open pool instead. The site went live in 1998 on a grant from the National Institute of Mental Health. It now holds over 3,000 items and more than 250 scales, all public domain by design.
That decision is why a serious Big Five questionnaire costs you nothing, and why we can offer one with no license agreement. There is a cost. Quality varies wildly across the web, because anyone at all can publish an IPIP test and nobody checks their scoring.
The versions you are most likely to meet
We offer two of them, plus a third Big Five measure from a different author.
| Test | Items | Measures | Time |
|---|---|---|---|
| TIPI | 10 | Five traits, roughly | 1 minute |
| IPIP-50 | 50 | Five traits | 8 minutes |
| IPIP-NEO-120 | 120 | Five traits, built from 30 sub-scales | 20 minutes |
The IPIP-50 is the one most people mean by "the IPIP". It uses Goldberg's Big-Five Factor Markers, published in 1992. Ten questions per trait.
The IPIP-NEO-120 is a different lineage. It is a short form of the 300-item IPIP-NEO, built by John A. Johnson and published in 2014. Its questions group into 30 narrower sub-scales, six inside each trait. That is what makes it more precise than the 50. Survey Doctor reports the five trait scores, not 30 separate sub-scores.
The TIPI is not IPIP at all. It comes from Gosling and colleagues in 2003 and is also free for any use. Two questions per trait is very few, and it was built for studies where a longer questionnaire simply will not fit. It is listed here because anyone comparing free Big Five tests will meet it.
If you want help choosing, we wrote a longer comparison of the 50-item and 120-item versions.
How it relates to the commercial NEO test
You may see the IPIP-NEO described as a copy of the NEO-PI-R. Close. Not quite right.
The NEO-PI-R is a copyrighted questionnaire sold by a publisher. The IPIP-NEO measures the same five traits and the same 30 sub-traits. But the questions were written from scratch and placed in the public domain. It was built to match what the NEO measures, not to reproduce it. The names are similar because the target is.
What a Big Five score can and cannot tell you
Two things worth knowing before you read your result.
A raw score is not a percentile. Score 38 on Conscientiousness out of a possible 50 and you have not ranked above 38% of people. Or 76% of them. A percentile has to come from a norm sample. We show one beside every IPIP-NEO-120 score, built from 339,977 adult responses the test's author published. The IPIP-50 gets bands only, because no equivalent sample exists for it.
None of this is a mental health screening. Personality questionnaires measure ordinary differences between people. No score, and no combination of scores, indicates a disorder or gives a diagnosis. Trying to work out whether something is wrong, rather than what you are like? A personality test is the wrong tool. Start with which assessment to take.
Common questions
Is the IPIP free for commercial use?
Yes. The items and scales are public domain, so they can be used for any purpose without permission or fees. Paid products included. This is unusual: most well-validated personality and mental health questionnaires are copyrighted and licensed.
Is a free test as good as a paid one?
For the Big Five, the gap is much smaller than the price difference suggests. IPIP scales were built and validated against the commercial questionnaires they parallel, and they hold up. What you lose is the publisher's manual, their norm tables, and their support.
What does the NEO in IPIP-NEO stand for?
Neuroticism, Extraversion, Openness. The original NEO Inventory measured only those three. Agreeableness and Conscientiousness came later, and the name stuck.
Which version should I take?
Take the IPIP-50 if you want your five trait scores in under ten minutes. Take the IPIP-NEO-120 if you want the detail underneath them and do not mind twenty.
Can I use IPIP questions in my own research?
Yes. You can edit them, translate them, and mix them with other questions. The IPIP site asks you to cite the source, which is good practice rather than a legal condition.