# Percentile

Pronunciation: /pərˈsɛn.taɪl/ Explain

A percentile ranking (or centile) is the value of a data item below which a certain percent of observations fall. If 27% of people in the United States are under 20 years of age, The 27th percentile ranking for the age is 20 years. If you are 20 years old, you are in the 27th percentile.

### How to calculate percentile ranking

To find a percentile ranking of a data value:

1. Count the number of data items below the data value.
2. Count the total number of data items.
3. Divide the number of data items below the data value by the total number of data items.
4. Convert the quotient to a percentage.
5. Round the percentage to the nearest whole number.

Example 1: Scores on a test. The scores on a test were as follows: 47, 55, 62, 64, 73, 73, 75, 78, 78, 78, 80, 81, 82, 83, 86, 86, 87, 90, 92, 98, 98, 99. What is the percentile ranking of a score of 86?

StepDescriptionCalculation
1 Count the number of data items below the value of 86. There are 14 data items below the value of 86.
2 Count the total number of data items. There are a total of 22 data items.
3 Divide the number of data items below 86 by the total number of data items. 14/22 = 0.636363.
4 Convert the quotient to a percentage. 0.636363·100 = 63.6363%.
5 Round the percentage to the nearest whole number. 63.6363% rounded to the nearest whole number is 63%.
-ConclusionThe percentile ranking of a score of 86 on this test is 63rd percentile. A score of 86 is greater than 63% of the scores on the test.
Table 1: Calculating percentile example 1

### References

1. McAdams, David E.. All Math Words Dictionary, percentile. 2nd Classroom edition 20150108-4799968. pg 136. Life is a Story Problem LLC. January 8, 2015. Buy the book