📈 Percentile Calculator
Enter a score along with the group’s mean and standard deviation to estimate what percentile that score falls in, assuming a normal distribution.
What a percentile rank means
A percentile rank tells you what share of a group scored at or below a given value. For example, a percentile of 84 means the score is higher than roughly 84% of the group.
How this calculator works
This calculator assumes your data follows a roughly normal (bell-curve) distribution, which is a common and widely used approximation for test scores, measurements, and many natural phenomena. It first converts your score to a z-score — the number of standard deviations your score is from the mean — using the formula z = (score – mean) / standard deviation. It then converts that z-score into a percentile using the standard normal distribution.
Real-world data doesn’t always follow a perfect normal distribution, so treat the result as a close estimate rather than an exact rank. This tool is intended for general educational and planning purposes.