What percentile is an average IQ?

IQ 100 is the mean and sits at percentile rank 50. About 68% of people score between 85 (percentile 16) and 115 (percentile 84).

How do I convert an IQ of 120 to a percentile?

On the mean-100, standard-deviation-15 scale, IQ 120 corresponds to about percentile rank 91, meaning roughly 9% of the reference population scores higher.

Is percentile rank the same as the percentage of correct answers?

No. Percentile rank compares you with other people, while the percentage of correct answers depends on the test's length and difficulty. The same percentage of correct answers can map to very different percentile ranks on different tests.

IQ percentile calculator

Convert between IQ scores and percentile ranks on the standard scale, or start from a percentile to find the matching IQ. The conversion uses the common normal model with a mean of 100 and a standard deviation of 15.

Convert IQ to percentile

Convert an IQ score to a percentile, or find the IQ score that corresponds to a percentile.

Estimated conversion

IQ score: 120
Percentile: 90.88
Scores below: 90.88%
Scores above: 9.12%

Reference group

Theoretical normal distribution: mean 100, standard deviation 15. These percentages describe this model, not UniversalIQTest.com participants or a measured population.

Normal IQ distribution

How the conversion works

p = 100 × Φ((IQ − 100) / 15)

IQ = 100 + 15 × Φ⁻¹(p / 100)

Φ is the cumulative distribution function of the standard normal distribution; Φ⁻¹ is its inverse. A percentile is a rank, not the percentage of questions answered correctly.

How to read the result

A percentile rank is a position relative to the reference population. If an IQ of 120 corresponds to about the 91st percentile, that means roughly 91% of the reference group scores below 120.

Percentile rank is not the percentage of questions answered correctly. 60% correct on an easy test and 60% correct on a hard test lead to very different percentile ranks.

Want your own result with all the context? Take the free 40-question test.

Take the IQ test

Explore IQ scores

Frequently asked questions

What percentile is an average IQ?: IQ 100 is the mean and sits at percentile rank 50. About 68% of people score between 85 (percentile 16) and 115 (percentile 84).
How do I convert an IQ of 120 to a percentile?: On the mean-100, standard-deviation-15 scale, IQ 120 corresponds to about percentile rank 91, meaning roughly 9% of the reference population scores higher.
Is percentile rank the same as the percentage of correct answers?: No. Percentile rank compares you with other people, while the percentage of correct answers depends on the test's length and difficulty. The same percentage of correct answers can map to very different percentile ranks on different tests.

This page describes the theoretical normal distribution (mean 100, standard deviation 15) for educational purposes. It is not a clinical assessment or a diagnosis.