The Library · Collection 01

Personality & Individual Traits

Everything here is self-report: it measures how you see yourself, filtered through how honestly you answer. That's a real limitation — and still, these instruments predict life outcomes, replicate across cultures, and beat every popular typology on the market. Where a scale has a known weakness, the annotation says so.

Broad trait models

The Big Five is the most replicated structure in personality science — five broad dimensions that reliably emerge across languages and cultures. HEXACO is its strongest challenger, adding a sixth factor with real moral teeth. If you take only one instrument on this page, make it one of these.

IPIP-NEO (120 / 300)

Strong evidenceFree · scored onlineFree · items + scoring key

The Big Five, with six facets per domain · 120 items · ~25 min

Public-domain item sets built to proxy the commercial NEO-PI-R; they correlate strongly with it and are free to use for any purpose, including embedding in your own tools. The 120-item version is the sweet spot between facet-level detail and your patience; the 300-item version adds precision you probably don't need. The open-source bigfive-test.com implementation gives clean, facet-level results with no account.

BFI-2

Strong evidenceFree · items + scoring key

The Big Five, with three facets per domain · 60 items · ~10 min

Soto & John's 2017 revision of the Big Five Inventory — probably the best short Big Five instrument available: carefully built facet structure and item balancing to control acquiescence bias. Free for personal and research use from the authors, with 30-item (BFI-2-S) and 15-item (BFI-2-XS) short forms when time matters more than facets.

HEXACO-PI-R

Strong evidenceFree · scored onlineFree · items + scoring key

Six trait dimensions: the familiar five plus Honesty–Humility · 100 items · ~15 min (60- and 200-item forms too)

Adds Honesty–Humility (sincerity, fairness, greed-avoidance, modesty) to the standard five — the personality dimension most directly relevant to a moral profile, and the strongest personality-level predictor of ethical behavior and resistance to corruption. Growing lexical evidence across languages supports it as a genuine sixth factor rather than a Big Five variant. The official site, run by the model's creators (Lee & Ashton), offers free self- and observer-report forms — having someone who knows you well fill in the observer form is quietly one of the most informative things on this page.

NEO-PI-3 / NEO-PI-R

Strong evidenceProprietary · paid

The Big Five, six facets per domain — the commercial standard · 240 items · ~40 min

Costa & McCrae's instrument is the commercial gold standard the IPIP-NEO was built to mirror. It's proprietary (Psychological Assessment Resources), and for self-use there's little reason to pay: the free IPIP-NEO delivers nearly identical information. Listed here mostly so you know what the citation trail points to.

TIPI

Moderate evidence· brief by designFree · items + scoring key

The Big Five at domain level only · 10 items · ~1 min

Gosling's Ten-Item Personality Inventory deliberately trades reliability for brevity — two items per trait, written for research settings where every second counts. Fine as a rough sketch or for tracking; don't expect facet insight or high internal consistency, because it wasn't built to have either.

Dark traits

The unflattering counterpart to Honesty–Humility. One measure you'll meet all over the internet — the 12-item Dirty Dozen — is deliberately not listed: multiple independent factor-analytic studies find it captures general disagreeableness more than three distinct traits. Use the SD3 or SD4 instead.

Short Dark Triad (SD3)

Strong evidenceFree · scored onlineFree · items + scoring key

Machiavellianism, narcissism, and subclinical psychopathy · 27 items · ~5 min

The well-established brief measure of the three classic dark traits, widely replicated. Known wrinkle: the Machiavellianism and psychopathy subscales correlate more strongly with each other than the theory would like. Self-report on socially undesirable traits is inherently noisy — answer as the person you are on a bad day, not the one you present at work.

Short Dark Tetrad (SD4)

Moderate evidence· newerFree · items + scoring key

The Dark Triad plus everyday sadism · 28 items · ~5 min

Paulhus's 2021 update adds sadism as a fourth trait and revises the Machiavellianism items specifically to reduce their overlap with psychopathy. Initial cross-cultural replications (Polish, Romanian, Spanish samples) are promising, but it's still accumulating the independent evidence the SD3 already has.

Empathy

Interpersonal Reactivity Index (IRI)

Strong evidenceFree · items + scoring key

Four distinct facets: perspective-taking, empathic concern, personal distress, and fantasy · 28 items · ~5 min

The standard multidimensional empathy measure, cited over ten thousand times. Its lasting contribution is refusing to treat empathy as one thing: cognitive empathy (perspective-taking) and affective empathy (empathic concern) are separated from the tendency to be personally overwhelmed by others' distress — three very different profiles that a single 'empathy score' would blur together.

Empathy Quotient (EQ)

Moderate evidenceFree · items + scoring key

Self-reported empathy as a single score · 60 items · ~10 min

Baron-Cohen's scale from the Cambridge Autism Research Centre, widely used especially in autism research. Debates persist about its factor structure and about how well self-reported empathy tracks actual empathic accuracy — a gap that applies to every scale in this section, but is documented most thoroughly here. Useful alongside the IRI rather than instead of it.

Single-construct classics

Narrow, heavily used scales that measure exactly one thing. Short enough that there's little reason not to add them to a self-assessment session.

Rosenberg Self-Esteem Scale

Strong evidenceFree · items + scoring key

Global self-esteem · 10 items · ~2 min

The standard self-esteem measure since 1965, translated into dozens of languages and still the default in research. Ten items, simple scoring, no gimmicks — a model of what a good brief scale looks like.

Grit Scale (Grit-S)

Moderate evidence· contestedFree · scored online

Perseverance and consistency of long-term interests · 10 items · ~3 min

Duckworth's scale, taken and scored on her site. Include it with eyes open: meta-analytic work finds grit correlates so strongly with Big Five conscientiousness that it adds little incremental prediction, and the 'consistency of interests' half carries most of the redundancy. Better read as a conscientiousness-adjacent lens than as a distinct trait.

Self-Compassion Scale (SCS)

Moderate evidenceFree · scored onlineFree · items + scoring key

How you relate to yourself in difficulty — kindness vs. judgment, common humanity vs. isolation, mindfulness vs. over-identification · 26 items · ~5 min

Neff's scale anchors a large and growing literature. The main psychometric argument is whether the six subscales justify a single total score — the negatively worded 'self-coldness' items may behave differently from the rest. Still the standard instrument, and the subscale profile is more informative than the total anyway.