Enter the total number of observations into the calculator to determine the 40th percentile. This calculator can also evaluate any of the variables given the others are known.

40Th Percentile Formula

The following formula is used to calculate the 40th percentile of a data set.

P40 = 1 + (n - 1) * 0.40


  • P40 is the 40th percentile of the data setn is the total number of observations in the data set

To calculate the 40th percentile, subtract 1 from the total number of observations, then multiply the result by 0.40. Add 1 to the product to get the 40th percentile.

What is a 40Th Percentile?

A 40th percentile is a statistical measure that indicates the value below which 40 percent of the data points in a dataset may be found. In other words, 40 percent of the observations are less than or equal to this value. It is often used in statistics to provide a relative standing of a value within a dataset.

How to Calculate 40Th Percentile?

The following steps outline how to calculate the 40th Percentile using the formula: P40 = 1 + (n – 1) * 0.40

  1. First, determine the total number of observations in the data set (n).
  2. Next, subtract 1 from the total number of observations (n – 1).
  3. Multiply the result from step 2 by 0.40.
  4. Add 1 to the result from step 3.
  5. Finally, calculate the 40th Percentile (P40).
  6. 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.

Total number of observations (n) = 50

40th Percentile (P40) = ?