IQ 78

An IQ of 78 is 22 points below the average of 100, or 1.47 standard deviations. This site classes it as Below Average. About 7.1% of people score at or below 78, which in a class of 30 is roughly 2 people. It sits 8 points past the 70 mark and 7 short of 85.

A score in the 70s on one online test is not a diagnosis of anything. Only a qualified professional, such as a clinical or educational psychologist, can assess anything clinical, and they never rely on a single number.

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.

Retest gains of a few points are well documented once a format is familiar. First attempts at any unfamiliar kind of test tend to be the least representative.

Think of 78 as the middle of a window. On a second attempt the same person could plausibly land at 83, which is higher than 12.9% of people, or at 73. That is before counting the extra noise an unsupervised online test adds.

Professional assessments combine several subtests (verbal, visual, memory and speed) and look at the pattern between them, not just one total. A single online total cannot show that pattern.

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.

Near 78 the curve is steep, so a few points change your percentile a lot. Going from 78 to 81 would lift you from the 7.1st to the 10.3rd percentile. These are the usual reasons scores swing:

• Stress and mood. Worry takes up working memory. People who feel anxious about tests often score below their usual level.
• Familiarity. People who have seen matrix-style puzzles before tend to do better on them. That is a practice effect, not a change in underlying ability.
• Timing and comfort. Hunger, a headache or testing late at night can all pull a score down on the day.

On a bell curve with a mean of 100 and a standard deviation of 15, about 7.1% of people score 78 or lower. Applied to whole populations:

Scoring 78 or lower is about 1 in 14. At 83 or lower it becomes 1 in 8, and at 73 or lower 1 in 28, which shows how quickly the curve fills up towards the middle.

What your 78 could really be. If you retook a well-made test, landing at 73 or at 83 would be unremarkable. That is the difference between beating 3.6% and 12.9% of people, and short online tests are noisier still.

Which scale was it on? A 78 reported on an SD 16 scale converts to about 79 on the usual SD 15 scale, and one from an SD 24 scale (seen in some Cattell-style results) to about 86. Check which scale your score report used.

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 78. That is not because famous people score higher. Estimates are only attempted for people with extraordinary records, which leaves ordinary scores unrepresented.

Nearby scores and the round-number landmarks, so you can see how quickly the percentile changes around 78. Every row links to that score's page.

People with an IQ of 78 typically score about 740 on the SAT and about 12 on the ACT composite. Scores vary a lot from person to person, so the range shows where about four in five land.