Test types
The Mensa IQ test
Mensa's requirement is the 98th percentile of the general population — about 130 on a standard scale, not the 140 that circulates. Here is how entry actually works.
The threshold, stated properly
Mensa admits people who score at or above the 98th percentile on an approved, supervised intelligence test. That is the requirement, and it is expressed as a percentile rather than a score for a reason.
On a scale with a standard deviation of 15 — the Wechsler tests, the modern Stanford–Binet — the 98th percentile is about 130. On the Cattell scale, with a standard deviation of 24, the same percentile is around 148. Both figures describe the same rarity: roughly one person in fifty.
The 140 that circulates online belongs to neither scale and appears to be a folk memory of Terman's 1916 “genius” threshold. It has never been Mensa's requirement.
Quoting the threshold as a percentile rather than a number sidesteps the whole scale problem. A score of 132 means the 98th percentile on one scale and the 91st on another; a percentile means the same thing everywhere.
The two routes in
Route one: Mensa's own supervised test. National Mensa organisations run supervised testing sessions, usually for a modest fee. The test is administered in person under standard conditions, and the result is either sufficient or it is not. There is no partial credit and no appeal to a different interpretation.
Route two: prior evidence. Mensa accepts results from a published list of approved tests, provided the test was properly supervised and the documentation is acceptable. The list varies by country and typically includes the WAIS, the Stanford–Binet, the Cattell Culture Fair, and in some countries older standardised admissions tests taken before specific dates.
Both routes require supervision. That is the whole point of the requirement: an unsupervised result cannot verify who answered, under what conditions, or how many times.
Why no online test qualifies
Mensa's own online offering is explicit about this. It is a practice or workout exercise, it is not supervised, and it does not qualify anyone for membership. Nor does any other web test, free or paid, however the site describes it.
A site claiming that its test qualifies you for Mensa is either uninformed or dishonest. It is a useful signal either way, and worth applying to everything else on that site.
What an online test can reasonably do is tell you whether a supervised session is worth booking. If you are scoring near the top band on a decent free test, the fee for a supervised sitting may be worth paying. If you are scoring in the middle, it probably is not, and that is a genuinely useful thing to find out for nothing.
Can you prepare?
Familiarisation and coaching are different, and the distinction is the same one that applies everywhere in testing.
Familiarisation — knowing the format, having seen matrix and series items before, understanding the instructions — removes a source of error that has nothing to do with your reasoning. Doing this is sensible and nobody objects to it.
Intensive coaching on the specific item types raises your score on those item types without raising the ability. Practice effects on reasoning tests are well documented and worth several points, concentrated on the first repeat.
Whether that matters to you depends on what you want from membership. Coaching your way over a percentile line gets you a card; it does not get you the thing the card is supposed to indicate.
What membership actually is
Mensa is a social organisation with an entry test. It runs local groups, special interest groups, publications and gatherings. It is not a professional credential, it does not appear usefully on a CV, and it confers no standing outside itself.
People who enjoy it tend to enjoy the social side. People who join expecting the score to open doors are generally disappointed, and the organisation has never claimed otherwise.
There are also other high-IQ societies with higher thresholds — the 99.9th percentile and beyond. The higher the threshold, the smaller the pool of tests that can measure it reliably, and above about the 99.9th percentile the norm samples underlying any test contain too few people to calibrate against. Societies at those levels are, in a measurement sense, sorting on extrapolation.
A norm sample of a few thousand people contains perhaps one person at the 99.97th percentile. Any threshold beyond that is defined by extending a curve rather than by comparing against measured people.
In short
| Question | Answer |
|---|---|
| What score do you need? | The 98th percentile — about 130 on a scale with SD 15, about 148 on Cattell |
| Is it 140? | No. That figure has never been the requirement |
| Does an online test count? | No, including Mensa's own practice test |
| Which tests are accepted? | A published list per country, all supervised; commonly the WAIS, Stanford–Binet and Cattell |
| Can you retake? | Policies vary by national organisation; most limit attempts |
| Is it a credential? | No. It is a social organisation with an entry test |
Questions
Questions people ask
What IQ do you need for Mensa?
The 98th percentile, which is about 130 on a scale with a standard deviation of 15 and about 148 on the Cattell scale. It is not 140.
Can I join Mensa with an online IQ test result?
No. Mensa requires a supervised test, either its own or one from its approved list. Its own online exercise explicitly does not qualify anyone.
Which tests does Mensa accept?
A published list that varies by country, typically including the WAIS, the Stanford–Binet and the Cattell Culture Fair, always with proof of supervised administration.
How much does Mensa testing cost?
National organisations set their own fees, usually a modest one-off charge for a supervised session. Membership dues are separate and annual.
Is Mensa membership worth it?
As a social organisation, for people who enjoy that kind of thing. It is not a professional credential and confers no standing outside itself.
Related reading
Find out where you land
Ten reasoning questions, an instant band and an explanation for every answer.