Sort the data set from least to greatest
Find the value whose percentile you want
Count how many values are below that value
Count how many values are equal to that value
Use the percentile formula: Percentile = (number below + 0.5 × number equal) ÷ total number of values × 100
If your method requires it, use the rank formula: Rank = (percentile ÷ 100) × (n + 1)
Locate the rank in the ordered data set
Interpolate between adjacent values if the rank is not a whole number
Report the resulting percentile value or percentile rank