What does an IQ of 78 mean?

An IQ of 78 is classified as Well below average. It is higher than 7% of people — roughly 1 in 14.

Higher than 7%
How rare 1 in 14
From the average −1.47
Classification Well below average

IQ scores follow a bell curve centred on 100, with a standard deviation of 15. About 68% of people score between 85 and 115, and about 95% between 70 and 130.

Curious where you would land? Take the free 60-question test and find out.

What it means in practice

Mensa admits the top 2% — about IQ 130 on a test with a standard deviation of 15. A score of 78 is 52 points below that line.

No test measures IQ exactly. A typical standard error is about 5 points, so a result of 78 really means "somewhere between 73 and 83" — and a second test on another day can land anywhere in that range.

For a child the number compares them with others of the same age, not with adults. IQ scores are age-normed, so a 10-year-old and a 40-year-old with the same score are each equally far ahead of their own age group.

Nearby scores

75 76 77 79 80 81

IQ chart: the IQ scale from 70 to 145 →

Frequently asked questions

Is an IQ of 78 good?

An IQ of 78 falls in the "Well below average" range and is higher than 7% of people. Any single test is an estimate, so treat it as a range rather than an exact figure.

What percentile is an IQ of 78?

An IQ of 78 sits at about the 7 percentile, which means roughly 1 in 14 people score at least this high.

Learn about IQ

What Is the Average IQ? The Number 100 Explained Why the average IQ is always 100, what the normal range looks like, and what average really means. What Is a Good IQ Score? IQ Percentiles & the Bell Curve Explained How to read IQ scores: the bell curve, the average of 100, and what percentiles actually tell you. The IQ Bell Curve Explained: Distribution & Standard Deviation How the normal distribution shapes every IQ score — the bell curve, standard deviation, and the 68-95-99.7 rule.

Curious where you would land? Take the free 60-question test and find out.