What IQ do you need for Mensa?
Last updated 1 August 2026
The rule is simpler than the numbers make it look: Mensa admits anyone who scores in the top 2% of the population on an approved, supervised test. What that means as an IQ number depends entirely on which scale the test uses — 130 on the modern SD 15 convention, 132 on SD 16, or 148 on the Cattell III B used by British Mensa. Same percentile, three different numbers.
The top 2%, on every scale
| Scale | Qualifying score (98th percentile) | Where you meet it |
|---|---|---|
| SD 15 (modern standard) | 130 | WAIS-IV, WAIS-5, Stanford-Binet 5, most modern tests, this site |
| SD 16 (older Stanford-Binet) | 132 | Legacy Stanford-Binet scores |
| SD 24 (Cattell) | 148 | Cattell III B, the supervised test used by British Mensa |
This single conversion explains most of the confusion around Mensa scores. Someone who announces a Mensa-qualifying 148 has not out-scored someone with a Wechsler 135 — the 148 is a Cattell number, and both sit near the top 2% line. Whenever two Mensa-related numbers disagree, convert both to percentiles before concluding anything.
Which tests does Mensa accept?
Mensa recognises around 200 standardised tests, provided the sitting was supervised and professionally administered. These are the ones people most often already hold a score from.
| Test | Scale | Qualifying score |
|---|---|---|
| WAIS-IV / WAIS-5 | SD 15 | Full Scale IQ 130 |
| Stanford-Binet 5 | SD 15 | 130 |
| Stanford-Binet (older editions) | SD 16 | 132 |
| Cattell III B | SD 24 | 148 |
| Cattell Culture Fair Scale III | SD 24 | 98th percentile |
The Culture Fair paper is entirely non-verbal, which is why British Mensa offers it alongside the Cattell III B. It is worth requesting if English is not your first language, or if you are dyslexic and would rather not be reading under time pressure. You have to ask for it when booking; it is not the default.
How admission actually works
There are two routes. The first is sitting a supervised test session administered by Mensa itself, offered at test centres around the UK on a regular calendar. The second is submitting prior evidence: a qualifying score from a supervised, professionally administered test — such as a Wechsler assessment scored by an educational or clinical psychologist — can be accepted as-is.
What does not qualify, from any provider, is an unsupervised online score. Online tests, including ours, have a different job: they are the inexpensive, low-stakes way to find out whether you are close enough to the threshold to make a supervised sitting worth the fee and the morning. A result comfortably above the 98th percentile on a well-normed online matrix test is a good signal; a result around the line means a supervised test could go either way.
Sit the supervised test
British Mensa runs proctored sessions at test centres across the UK on a regular calendar. The standard paper is the Cattell III B, 150 questions under timed conditions. It is a demanding sitting rather than a half-hour quiz, and results follow by post within a few weeks.
Check the current fee and dates on Mensa's own site, as both change.
Submit a score you already have
If you have ever sat a supervised WAIS, Stanford-Binet, Cattell or one of the other recognised instruments, that certificate may already qualify you. A great many people hold a qualifying score from a school, clinical or occupational assessment without ever realising it.
You submit the documentation with an evaluation fee, and it is reviewed rather than re-tested.
How rare is Mensa level, really?
Top 2% sounds exclusive, and statistically it is: in a full double-decker bus of 75 people, one or two sit at this level. But scaled to a population, rarity turns into large absolute numbers — roughly 1.3 million people in the UK are at Mensa level, of whom only a small fraction ever test or join. If you qualify, you are rare company, but far from alone.
It is also worth knowing that at and above this level, tests begin to strain. Ceiling effects mean an ordinary test distinguishes 130 from 145 poorly, which is why Mensa cares only about clearing the 98th percentile line, not about how far past it a score claims to reach.
Want to know if a supervised test is worth booking? Take the 30 question matrix test and see your percentile first.
Start the free IQ test30 questions. 25 minutes. No registration. Full report £9.99.