IQ Percentile Calculator
Convert IQ scores to percentiles (or percentiles to IQ scores) using the normal distribution. Use the standard IQ model (mean 100, SD 15) or enter any mean and standard deviation. Includes percentile rank, inverse normal conversion, and rarity ("1 in X") estimates.
Normal Distribution Calculator
Enter a score or probability to compute percentile rank and rarity.
About IQ percentiles
This tool converts between IQ scores and percentiles using a normal distribution. The default settings (mean 100, SD 15) match the most common IQ scale, but you can enter any mean and standard deviation for other standardized tests.
How to convert IQ to percentile
Enter an IQ score, then click Calculate. The calculator returns the percentile (as a probability between 0 and 1) and shades the area under the curve. For example, an IQ of 130 is roughly the 98th percentile.
Convert percentile to IQ score
Enter a percentile as a probability (e.g., 0.975), then click Calculate. The tool computes the corresponding IQ score using the inverse normal distribution.
What does "1 in X" mean?
"1 in X" is an intuitive rarity estimate based on the upper-tail probability. A percentile of 0.99 is about 1 in 100. Higher percentiles produce much larger "1 in X" values.
Does this assume a normal distribution?
Yes. The conversions and chart assume a normal distribution defined by your mean and SD. This is a common model for IQ and many standardized test scores.