Enter your score, mean, and standard deviation into the calculator to determine your percentile.

Percentile Calculation Formula

The following formula is used to calculate the percentile from your score.

Percentile = 0.5 * (1 + erf((Score - Mean) / (StdDev * sqrt(2)))) * 100

Variables:

  • Score is the individual score you received.
  • Mean is the average score of the group.
  • Standard Deviation (StdDev) is a measure of the spread of scores in the group.

To calculate the percentile, plug in the score, mean, and standard deviation into the formula. The result will be the percentile, indicating the percentage of scores that fall below your score.

What is Percentile Calculation?

Percentile calculation refers to the process of determining the rank of a score in a group of scores. It is a statistical measure that indicates the relative standing of a score in comparison to other scores. Proper percentile calculation is essential for understanding how an individual score compares to the overall distribution of scores, which is useful in educational assessments, standardized testing, and various performance evaluations.

How to Calculate Percentile?

The following steps outline how to calculate the percentile using the given formula.


  1. First, determine your score, the mean score, and the standard deviation of the group.
  2. Next, use the formula from above: Percentile = 0.5 * (1 + erf((Score – Mean) / (StdDev * sqrt(2)))) * 100.
  3. Calculate the value inside the erf function.
  4. Calculate the error function (erf) of the value.
  5. Multiply the result by 0.5 and add 0.5.
  6. Multiply the final result by 100 to get the percentile.
  7. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Score = 85

Mean = 75

Standard Deviation = 10

FAQ

1. What is a percentile?

A percentile is a measure that indicates the value below which a given percentage of observations fall. For example, the 50th percentile is the value below which 50% of the observations may be found.

2. How is a percentile different from a percentage?

A percentile represents the rank of a score within a group, whereas a percentage represents a part of a whole. Percentiles are used in statistical analysis, while percentages are used in everyday calculations.

3. How often should I use the percentile calculator?

It’s helpful to use the percentile calculator whenever you need to determine the relative standing of a score within a group, such as in test results, performance evaluations, or statistical analysis.

4. Can this calculator be used for different types of scores?

Yes, you can use this calculator for different types of scores as long as you have the mean and standard deviation of the group of scores.

5. Is the calculator accurate?

The calculator provides an estimate of the percentile based on the inputs provided. For exact figures, it’s best to consult statistical analysis tools or software.