Outlier Calculator
Flag outliers in a data set using the 1.5 × IQR rule.
What is Outliers?
An outlier by the standard rule is a value more than 1.5 interquartile ranges below Q1 or above Q3. It is the definition a box plot draws as a separate point, and the one most mark schemes mean when they say "outlier" without qualification — though a stricter 3 × IQR version also exists for extreme outliers.
How it works
The quartiles and the interquartile range come from the same engine call as every other page in this category, and the fences are computed from them rather than from the range, so a value can only be flagged if it genuinely falls outside the middle half's margin. The fences are shown next to the flagged values because "just past the fence at 47.75" and "400" are very different findings.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.