Formulas > Descriptive Statistics > Percentile

The pth percentile separates the bottom p% of the sorted values in a data set from the top p%.

For a data set , in which the values are sorted in ascending order,

pth percentile =
x1 if i ≤ 0
xn if i ≥ n
xi + a(xi+1 - xi) otherwise

where
i = floor(p(n+1)/100)
a = p(n+1)/100 - i.