Statistics Calculators

Outlier Calculator (1.5×IQR Rule)

Identify outliers in a dataset using the standard 1.5×IQR rule, along with the lower and upper fences.

Lower fence —

Upper fence —

Number of outliers —

Outlier values —

About the Outlier Calculator (1.5×IQR Rule)

The 1.5×IQR rule is the most common method for flagging outliers — values that sit unusually far from the bulk of the data. Any value beyond 1.5 times the interquartile range past Q1 or Q3 is considered an outlier.

Formula: Lower fence = Q1 − 1.5 × IQR · Upper fence = Q3 + 1.5 × IQR, where a value is an outlier if it falls outside these fences

This rule is what determines which points get plotted individually beyond the "whiskers" of a box plot, and is widely used as a quick, distribution-free way to screen data for entry errors or genuinely extreme values.