IQ 64

64 is below the middle of the curve, but it is far from unusual. Around 560,000 people in the UK would score 64 or lower on the same scale. It works out at 2.40 standard deviations under the mean, in the band this site calls Below Average.

A score under 70 on a single online test does not mean anything clinical. Only a qualified professional, such as a clinical or educational psychologist, can assess that, using supervised tests and a look at everyday functioning.

Plenty of valuable skills are learned mainly through practice. Trades, care work, hospitality, sport, driving and music all reward repetition and experience, and people keep improving at them for decades.

If you want to understand your result, think about which questions felt hard. Running out of time, losing track of a rule and second-guessing yourself are different problems, and each one has a different fix.

A 64 from one online test is best read as a range, not a point. Even a well-built, supervised test has a margin of error of roughly 5 points either side, so the same person could reasonably score anywhere from about 59 to 69. That spans the 0.31st to the 1.9th percentile.

Your screen, your connection, background noise and interruptions all affect a timed test. A phone in a busy room is a very different test from a quiet desk.

Time limits matter. Some people reason accurately but slowly, and a short, timed test turns that into a lower number than an untimed task would.

Small day-to-day changes are enough to move a score around 64. A shift of 5 points, from 64 to 69, would move you from the 0.82nd to the 1.9th percentile, so it helps to know what causes those swings.

• Sleep. A short night reliably hurts working memory and attention, the two things timed puzzles lean on hardest.
• Stress and mood. Worry takes up working memory. People who feel anxious about tests often score below their usual level.
• Language. Questions that rely on words or written rules favour native speakers. Visual puzzles reduce this effect but do not remove it.

Scoring 64 or lower is a 0.8% share of everyone. Scaled up to whole populations, that works out as:

The curve fills up quickly towards the middle. Moving from 64 to 69 adds about 1 percentage points of people at or below you, and moving down to 59 removes about 1.

What your 64 could really be. Treat any single score as the centre of a range. For a good supervised test, about 5 points either side is typical, so 64 really means somewhere from 59 to 69. Online tests are less precise than that.

Which scale was it on? Most modern tests use a standard deviation of 15, which is what this page assumes. If your 64 came from a test using an SD of 16, it is about 66 on the SD 15 scale. From an SD 24 scale, used by some Cattell-style reports, it is about 78.

Nobody famous has a verified IQ in most cases, and retrospective estimates are only made for a narrow group.

Our historical estimates start at 115, so nobody sits close to 64. That is not because famous people score higher. Estimates are only attempted for people with extraordinary records, which leaves ordinary scores unrepresented.

How 64 stacks up against the scores just around it and the round numbers people usually ask about. Each score links to its own page.