High IQ Societies: Mensa and the Groups Beyond It
Most people have heard of Mensa, but it is only the entry point to a whole tier of clubs built around a single idea: admit anyone whose test score sits above a fixed percentile, and let them find each other. Some set the bar at the top 2%. Others draw the line so high that only a few hundred people on Earth could ever qualify.
A high IQ society is exactly that — a membership organisation whose one entry requirement is a qualifying score on an accepted intelligence test. This guide maps the landscape, from the accessible and well-run to the ultra-exclusive and statistically shaky, as of 2026.
What counts as a high IQ society
The defining feature is the cutoff. Instead of interviewing you or judging achievements, these groups accept a number: your percentile rank on a standardized test. Mensa uses the 98th percentile (top 2%). Others go higher — the 99th, the 99.9th, even rarer. The higher the cutoff, the smaller and more exclusive the group, and the less reliable the underlying scores become.
| Society | Cutoff (percentile) | Approx. IQ (SD 15) | Rarity | Notes |
|---|---|---|---|---|
| Mensa | 98th (top 2%) | ~130 | 1 in 50 | Largest and most accessible; ~145,000 members |
| Intertel | 99th (top 1%) | ~135 | 1 in 100 | Founded 1966 |
| Triple Nine Society | 99.9th | ~146 | 1 in 1,000 | "999" refers to the percentile |
| Prometheus Society | 99.997th | ~160 | ~1 in 30,000 | Very small membership |
| Mega Society | 99.9999th | ~171 | ~1 in 1,000,000 | Famously tiny; entry tests disputed |
Treat the IQ columns as approximate. Different tests and standard deviations put the same percentile at different numbers, which is exactly where the trouble begins at the top.
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Mensa vs the more exclusive societies
Mensa is popular for a reason: the top 2% is rare enough to feel meaningful but common enough that real testing can measure it accurately, and its chapters run genuine social events worldwide. It is a functioning community, not just a certificate.
The rarer societies are a different proposition. At the 99.9th percentile and beyond, the pool of eligible people shrinks to thousands, then hundreds, then a handful. Membership becomes less about local meetups and more about correspondence, puzzles, and the identity of belonging to something exceedingly rare.
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Why ultra-high cutoffs are statistically shaky
Here is the honest problem. Standardized IQ tests are normed on large samples, but those samples thin out dramatically at the extremes. A test might have only a few dozen people near the top of its norming group, so the difference between a "160" and a "175" rests on very little data. The standard error of measurement — the built-in wobble in any score — also means an extreme score could easily be several points off.
That is why the most exclusive societies often rely on custom, unstandardized "power tests" with no time limit, and why their claimed cutoffs are frequently disputed even among enthusiasts. Above roughly IQ 160, the numbers are better understood as rankings on a particular puzzle set than as precise measurements of general intelligence.
Is joining worth it?
That depends entirely on what you want. If you enjoy the community, the events, and meeting people who think the way you do, Mensa in particular delivers a real, active network. If you are chasing an ultra-rare number as a badge, be clear-eyed that the number itself is far less solid than it looks. Either way, a society membership measures where you scored on one test — not your worth, your creativity, or what you will accomplish.
A little history and perspective
Mensa is the oldest of these groups, founded in 1946 in Oxford by Roland Berrill and Lancelot Ware with a simple, deliberately apolitical idea: create a society whose only entry criterion is intelligence, with no other qualification of race, religion, or background. That founding principle is why the entry test is the whole of the requirement. The more exclusive societies came later, mostly from the mid-twentieth century onward, each trying to draw the line further into the tail.
It is worth remembering that plenty of brilliant, accomplished people never join any of these groups, and plenty of members are ordinary people who happen to test well. A high score gets you through the door; it does not, by itself, predict what you will do once inside. The societies are best understood as communities of shared interest — puzzles, conversation, belonging — rather than as leaderboards of human worth. Approached that way, they can be genuinely rewarding; approached as proof of superiority, they tend to disappoint.
Frequently Asked Questions
Q: What is the hardest high IQ society to get into?
A: The Mega Society is among the most exclusive, claiming a one-in-a-million (99.9999th percentile) cutoff. In practice its entry tests are custom and disputed, because no standardized test can reliably measure that far into the tail.
Q: Is Mensa the only high IQ society?
A: No. Mensa is the largest, but there are many others with higher cutoffs — Intertel (top 1%), the Triple Nine Society (99.9th), Prometheus, and the Mega Society, among them.
Q: Are high IQ society scores accurate at the extremes?
A: Not very. Standardized tests are thinly normed above about IQ 145–160, so extreme scores carry large uncertainty. The rarest societies rely on custom tests whose cutoffs are often contested.
Q: How do I qualify for a high IQ society?
A: By submitting a qualifying score from an accepted test, or by sitting the society's own admission test. Each group publishes which tests and scores it accepts for its particular percentile cutoff.
References
Last updated: July 13, 2026
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