Outlier Calculator
Tukey fences • Q1/Q3 methods • value:count supported
Enter data
Separators: comma, space, newline, semicolon. Frequency format: value:count where count is a positive integer.
k
× IQR
Default is Tukey’s k=1.5. Use k=3 for extreme outliers.
Action
Enter values, then click Calculate.
Calculating…
Use this Outlier Calculator to identify possible low and high outliers with the interquartile range (IQR) and Tukey fence method.
Calculation Method
IQR = Q3 − Q1
For the standard 1.5 × IQR rule:
Lower fence = Q1 − 1.5 × IQR
Upper fence = Q3 + 1.5 × IQR
Values below the lower fence or above the upper fence are flagged as possible outliers.
Example
For the dataset:
2, 3, 4, 5, 6, 7, 8, 100
Using the split-half quartile method:
Q1 = 3.5
Q3 = 7.5
IQR = 7.5 − 3.5 = 4
Lower fence = −2.5
Upper fence = 13.5
Because 100 is above 13.5, it is flagged as a possible high outlier.
Important Note
A flagged value is not automatically an error and should not be deleted without investigation. Different quartile calculation methods can also produce slightly different Q1, Q3, and fence values.