What the tool does, how to run it, and what to expect from the result.
Tukey’s rule flags values below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR. For 2, 3, 4, 5, 5, 6, 7, 8, 9, 30: Q1 = 4, Q3 = 8, IQR = 4, so the fences are −2 and 14, and 30 is an outlier. Unlike a z-score cut-off, the rule does not assume a normal distribution.
A quick way to understand who this helps, what it solves, and where it connects next.
Students, teachers, analysts and researchers working with data.
Using the outlier calculator without installing anything or signing up.
Short answers for the questions people usually have before trying a utility like this.
Only if they are errors. A genuine extreme value is data; report it, or use the median and IQR, which it does not distort.
Beyond 3 × IQR from the quartiles. The 1.5 × IQR fences mark mild outliers.
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IQR = Q3 − Q1, with outlier fences
IQR = Q3 − Q1, with outlier fences. Free, instant, in your browser.
Any percentile of a list, and percentile rank
Any percentile of a list, and percentile rank. Free, instant, in your browser.
Geometric, arithmetic and harmonic means
Geometric, arithmetic and harmonic means. Free, instant, in your browser.
The middle value, with how it was found
The middle value, with how it was found. Free, instant, in your browser.
Most frequent value, with a frequency table
Most frequent value, with a frequency table. Free, instant, in your browser.
Q1, median and Q3 with a box plot
Q1, median and Q3 with a box plot. Free, instant, in your browser.
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Quartiles use the median-of-halves method taught in most textbooks and used by TI-83/84 calculators. Excel’s interpolated values are shown for comparison.