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Short answer
The International Personality Item Pool (IPIP) is a public-domain bank of over 3,000 personality items and over 250 scales at ipip.ori.org. Anyone may copy, edit, translate or shorten them for any purpose, without permission or a fee. “IPIP” names the pool, not one test, so a study must say which scale it used.
- What you must decide: which specific scale to use (for example the 50-item Big-Five markers, the 20-item Mini-IPIP or the 120-item IPIP-NEO-120), how to score it, and how to cite it.
- What the site does not give you: norms or interpretive manuals.
Definition and scope
The IPIP website describes itself as “A Scientific Collaboratory for the Development of Advanced Measures of Personality and Other Individual Differences.” It was launched in 1998 with an NIMH grant awarded to Dr. Lewis R. Goldberg, who also wrote most of its items. The home page lists 3,320 items in alphabetical order.
This page covers the psychology resource only. The abbreviation is also used for unrelated technology products and protocols.
Many IPIP scales were designed to measure constructs that existing inventories already measure. The site says the main form of validity evidence it offers is the correlation between an IPIP scale and the scale it was based on, shown in comparison tables. For background on how such evidence is judged, see the CASRAI guide to construct validity and the overview of psychometrics.
How the IPIP is used in practice
Administering the items
The IPIP site states that there is no standardized administration procedure. Users may present items online or on paper, in any order, mixed with non-IPIP items, with edited or translated wording, with shortened or combined scales, and with a binary or rating-scale response format. The site argues that slight variations in administration do not have profound effects on substantive research results. It offers a 50-item sample questionnaire as a formatting suggestion, not a requirement.
Scoring a scale
The site’s scoring instructions are short. For + keyed items, “Very Inaccurate” scores 1, “Moderately Inaccurate” 2, “Neither Inaccurate nor Accurate” 3, “Moderately Accurate” 4 and “Very Accurate” 5. For – keyed items the values run in reverse (5 to 1). The scale score is the sum of the item values.
Illustrative example (hypothetical respondent). The Mini-IPIP Extraversion scale has four items: “Am the life of the party” and “Talk to a lot of different people at parties” are + keyed; “Don’t talk a lot” and “Keep in the background” are – keyed. Suppose a respondent answers Moderately Accurate (4), Very Accurate (5), Very Inaccurate (reverse-scored to 5) and Neither Inaccurate nor Accurate (3). The scale score is 4 + 5 + 5 + 3 = 17, on a possible range of 4 to 20.
Interpreting scores
The IPIP site says it has no manuals or interpretive guides and no norms, because it considers most canned norms misleading. It recommends local norms computed from your own sample. One suggested scheme treats scores within half a standard deviation of the mean as average, which for normally distributed scores gives about 38% average, 31% low and 31% high. Another divides scores into quintiles. The site cautions against interpreting scores as categories or sorting respondents into groups based on their scores.
IPIP inventories and versions
The site’s multi-construct page lists lexical Big Five inventories, inventories based on the five-factor model, HEXACO and other personality inventories. The versions researchers most often ask about are below; every row comes from the IPIP site’s own pages.
| Version | Size and coverage | Author and citation on the IPIP site |
|---|---|---|
| Big-Five Factor Markers | Five factors; a 10-item and a 20-item scale for each factor, so 50 or 100 items | Goldberg (1992), Psychological Assessment, 4, 26–42 |
| Mini-IPIP | 20 items, four per Big Five factor, a short form of the 50-item measure | Donnellan, Oswald, Baird and Lucas (2006), Psychological Assessment, 18, 192–203 |
| IPIP representation of NEO-PI-R domains and facets | 30 facet scales; the norms page calls it the 300-item IPIP representation of the NEO PI-R | Goldberg (1999), in Personality Psychology in Europe, Vol. 7 |
| IPIP-NEO-120 | 120 items covering 30 facets | Johnson (2014), Journal of Research in Personality, 51, 78–89 |
| IPIP-NEO-60 | Represents the NEO-PI-R domains | Maples-Keller et al. (2019) |
IPIP personality test
The IPIP supplies items and keys, not a hosted test with norms. Because the site publishes no norms, a score from any implementation needs the local-norm or quintile approach above.
IPIP-NEO, IPIP-NEO-120 and “IPIP-NEO-300”
These are public-domain scales built to measure constructs similar to those in the NEO-PI-R, not the NEO-PI-R itself. The citation page notes that only a few IPIP scales have been explicitly named by their authors, and gives Johnson’s “IPIP-NEO-120” as an example. The site itself describes the facet inventory as the 300-item IPIP representation of the NEO PI-R. Scoring keys mark each item as + or – keyed and follow the scoring rule above.
IPIP 20
The 20-item measure is the Mini-IPIP. The IPIP site’s own note on it says “The Mini-IPIP” was not the best choice of label, because the IPIP is a pool of items, not the name of a particular inventory. The note adds that the Mini-IPIP authors scored the lexical Emotional Stability scale in reverse and labelled it Neuroticism, so that factor is scored differently from the original IPIP scale it was based on.
Where it matters for research practice
Permission and citation checklist
These points are taken from the IPIP permission and citation pages:
- No permission request is needed, and the site author and IPIP consultant do not need to be contacted.
- If a scale author has named the scale, use that name and cite the author, for example IPIP-NEO-120 (Johnson, 2014).
- For an unnamed scale, describe the scale it is based on, for example “the 50-item IPIP representation of the Goldberg (1992) markers for the Big-Five factor structure”, and cite both that source and the web page with the key.
- Never refer to a specific scale as “the IPIP”.
- Never use an overly general label such as “the Big-Five IPIP Inventory”. The site says there are over a half-dozen IPIP Big Five inventories.
- To cite the IPIP in general, the site suggests Goldberg et al. (2006), Journal of Research in Personality, 40, 84–96, or the IPIP website itself.
Scale length and reliability on the IPIP site
The IPIP site lists a Cronbach alpha for each scale and says its estimates are based on responses of the Eugene-Springfield Community Sample, not on your sample. Putting the listed values for the same five factors side by side shows the effect of scale length:
| Factor | Mini-IPIP (4 items) | 10-item scale | 20-item scale |
|---|---|---|---|
| Extraversion (Surgency) | .77 | .87 | .91 |
| Agreeableness | .70 | .82 | .88 |
| Conscientiousness | .69 | .79 | .88 |
| Emotional stability (Neuroticism) | .68 | .86 | .91 |
| Intellect or Imagination | .65 | .84 | .90 |
On these listed figures alpha rises with length for every factor: .65 to .77 for four items per factor, .79 to .87 for ten and .88 to .91 for twenty. The Mini-IPIP’s fourth factor carries the Neuroticism label and reversed scoring described above, and all values come from one community sample. For how to interpret alpha, see the guide to Cronbach’s alpha and the overview of reliability in research measurement.
IPIP datasets
According to the IPIP norms page, data from the Eugene-Springfield Community Sample underlie many of the statistics on the site and are available from the Harvard Dataverse at dataverse.harvard.edu/dataverse/ESCS-Data. It advises reading the file “Read Me First.txt” before using the data. The page also names two archives not officially associated with the IPIP project: Johnson’s data repository on the Open Science Framework (raw data for the 300-item IPIP representation of the NEO PI-R and the IPIP-NEO-120) and the Open-Source Psychometrics Project. For the Big Five markers the page recommends avoiding the project’s 19,719-case data set and using its IPIP-FFM-data-8Nov2018.zip file instead.
Common misunderstandings
- “The IPIP is a personality test.” It is a pool of items; each inventory built from it is a separate measure with its own length and citation.
- “Public domain means I can skip citation.” Permission is not needed, but the site publishes its own citation guidance, summarised above.
- “IPIP-NEO is the NEO PI-R.” The site’s NEO facet key is titled as preliminary IPIP scales measuring constructs similar to those in the 30 NEO-PI-R facet scales, and its main validity evidence is correlation with the scale each one represents.
- “There is a standard administration format.” The site says there is none. The 50-item questionnaire is a suggestion, and the response format is the researcher’s choice.
Sources
Figures and policies on this page reflect the IPIP website as of 7 November 2026.
- International Personality Item Pool home page: https://ipip.ori.org/
- Obtaining Permission: https://ipip.ori.org/newPermission.htm
- Citing IPIP Scales in Scientific Publications: https://ipip.ori.org/newCitation.htm
- IPIP Scale Scoring Instructions: https://ipip.ori.org/newScoringInstructions.htm
- Reliability and Validity of IPIP Scales: https://ipip.ori.org/ReliabilityValidity.htm
- Multi-Construct IPIP Inventories: https://ipip.ori.org/newMultipleconstructs.htm
- Big-Five Factor Markers: https://ipip.ori.org/newBigFive5broadKey.htm
- Mini-IPIP Scoring Key: https://ipip.ori.org/MiniIPIPKey.htm
- NEO Facets Key: https://ipip.ori.org/newNEOFacetsKey.htm
- Administering IPIP Measures: https://ipip.ori.org/New_IPIP-50-item-scale.htm
- Interpreting Individual IPIP Scale Scores: https://ipip.ori.org/InterpretingIndividualIPIPScaleScores.htm
- Norms and Data Sets: https://ipip.ori.org/newNorms.htm
- Goldberg, L. R., et al. (2006). The international personality item pool and the future of public-domain personality measures. Journal of Research in Personality, 40, 84–96. doi:10.1016/j.jrp.2005.08.007
- Johnson, J. A. (2014). Measuring thirty facets of the Five Factor Model with a 120-item public domain inventory: Development of the IPIP-NEO-120. Journal of Research in Personality, 51, 78–89. doi:10.1016/j.jrp.2014.05.003
